Systems and Methods for Producing Silicone Hydrogel Contact Lenses From a Polymerizable Composition

ABSTRACT

Systems and methods of manufacturing ophthalmic lenses, for example, silicone hydrogel contact lenses, are provided. The present systems and methods provide certain amounts of ultraviolet light to contact lens mold assemblies that comprise a silicone hydrogel precursor composition. For example, the systems and methods may provide ultraviolet light at an intensity from 20 μW/cm 2  to 4000 μW/cm 2 . The ultraviolet light intensity can be provided as substantially uniform levels to provide consistent curing for batches of silicone hydrogel contact lenses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. application Ser. No.11/200,644, filed Aug. 9, 2005, the entire contents of which are herebyincorporated by reference.

The present invention generally relates to systems and methods forproducing contact lenses, such as silicone hydrogel contact lenses. Morespecifically, the present invention relates to systems and methods forcuring or polymerizing lens precursor compositions to form siliconehydrogel contact lenses.

BACKGROUND

It is known that compositions comprising one or more olefinicallyunsaturated monomers together with a small but effective amount of apolymerization initiator which is responsive to ultraviolet radiation ofa given intensity and/or wavelength can be initiated or polymerized byexposure of the composition to the indicated intensity and/or wavelengthof ultraviolet radiation. It is also generally recognized that controlof the initiation and propagation of polymerization is difficult.Accordingly, in many conventional applications of ultraviolet-initiatedpolymerization, the polymerization has been sought to be controlled byvariations of the identity and/or amount of ultraviolet initiator, thepresence and/or amount of a polymerization inhibitor, and thecharacteristics of the ultraviolet radiation used to initiate thepolymerization itself.

Because of the relative difficulty of controlling the polymerizationcharacteristics and the properties of the resultant polymerized article,it has generally been considered that ultraviolet-induced polymerizationis not completely satisfactory as a means for producing polymerizedarticles which must pass exacting requirements as to the dimensions andthe physical properties such as structural integrity, surfacesmoothness, freedom from discernable irregularities in the internalstructure and surface finish, clarity, transparency, and the like.Contact lenses are noteworthy examples of such articles which aresubject indeed to numerous exacting criteria, by virtue of both thephysical reality that contact lenses with even minor defects areconsidered unwearable, and of the regulations governing such articlesprescribed by the U.S. Food and Drug Administration, among othernational and international authorities.

There is therefore a need for effective methods and systems forproducing articles such as contact lenses by means ofultraviolet-induced polymerization.

SUMMARY

Accordingly, new systems and methods for manufacturing contact lenses,for example, silicone hydrogel contact lenses, are provided. The systemsand methods are especially useful for the manufacture of lenses that aremolded in contact lens molds containing polymerizable lens precursorcompositions, for example, monomeric compositions comprisinglight-sensitive initiators.

The present invention is also particularly useful for the manufacture ofcontact lenses formed from materials requiring precise or even exactingcontrol over polymerizing conditions, for example, manufacture of lensesformed from materials requiring very low intensities of light, forexample ultraviolet light, to cause or initiate polymerization of lensprecursor compositions.

The present systems provide substantially constant and consistentillumination of filled contact lens molds during a polymerizationprocess. The present systems include one or more features or elements toprovide rapid exposure of contact lens molds containing a lens precursorcomposition to a uniform intensity of ultraviolet light and for a timeeffective in polymerizing the lens precursor composition in the lensmolds. The present systems can be automated and are configured toprocess large quantities of contact lenses, such as silicone hydrogelcontact lenses.

In one embodiment, a system for producing a contact lens, such as asilicone hydrogel contact lens, can be understood to comprise a housing,a first set of ultraviolet lamps located at a first region within thehousing, a second set of ultraviolet lamps located at a second regionwithin the housing, the second set of lamps being spaced apart from thefirst set of lamps to define a space to accommodate a plurality ofcontact lens mold assemblies, which comprise a lens precursorcomposition, to provide a substantially uniform exposure of the lensprecursor composition to ultraviolet light emitted from the first andsecond set of lamps.

In one embodiment, the contact lens mold assemblies are located on atray or carrier structured to hold the assemblies and simultaneouslyexpose two substantially opposing surfaces of the assemblies to theultraviolet light emitted from the lamps. In certain embodiments, thehousing comprises a conveyor system for directing the contact lens moldassemblies, or a tray of contact lens mold assemblies, from an input endtoward an output end of the housing. In other embodiments, the housingmay be devoid of a conveyor system, and the mold assemblies can remainin a substantially fixed position relative to the housing duringexposure to the ultraviolet light.

The present systems are structured to substantially simultaneouslyexpose all of the contact lens mold assemblies to a uniform amount ofultraviolet light throughout the curing process, including during theinsertion and removal stages of the curing process. For example, thelens precursor composition contained in the mold assemblies is notexposed to amounts of ultraviolet light that would be sufficient tocause premature polymerization of the lens precursor composition. Anyexposure of the lens precursor composition in the mold assemblies priorto the curing process would be insufficient to cause polymerization orcuring of the lens precursor composition that would adversely affect thefinal polymerized product. In certain embodiments, the housing comprisesone or more light shields effective in reducing or preventing prematureexposure of the lens precursor composition to the ultraviolet light. Thelight shields can be plates or other substantially flat surfacesdefining a path into the housing where the lens precursor compositioncan be polymerized. Or, light shields can be gates that interfere withmovement of the mold assemblies and/or interfere with the passage oflight from the housing which could cause premature exposure of the lensprecursor composition to the light. In addition, or alternatively, thepresent systems can include one or more guiding devices effective inmoving the lens mold assemblies into the housing at a relatively rapidrate compared to the entire curing process.

In a broad aspect of the invention, methods of manufacturing ophthalmiclenses, for example silicone hydrogel contact lenses, including extendedwear and daily wear silicone hydrogel contact lenses, are provided. Themethods generally comprise providing a mold defining a lens shapedcavity, providing a polymerizable composition in the lens shaped cavity,and exposing the mold and polymerizable composition therein topolymerizing radiation, for example, ultraviolet light, in order tofacilitate or at least assist in causing or to cause polymerization ofthe polymerizable composition in the mold.

Preferably, the polymerizable composition comprises a formulationcomprising one or more silicon-containing monomers and/orsilicone-containing macromers. Thus, it may be understood that thepresent systems and methods are effective in forming silicone hydrogelcontact lenses from silicon-containing monomeric compositions. In oneembodiment, the polymerizable composition is effectively polymerized bya method including a step of exposing the composition, for example,exposing a mold and the polymerizable composition therein to light inthe ultraviolet spectrum having an illumination intensity of betweenabout 100 μW/cm² or about 200 μW/cm² or about 300 μW/cm² and about 900μW/cm² or about 1000 μW/cm² or about 2000 μW/cm². In a preferredembodiment, the polymerizable composition is effectively polymerized byexposing the mold and the polymerizable composition to light in theultraviolet spectrum having an illumination intensity of between about300 μW/cm² and about 1000 μW/cm². In certain embodiments, theillumination intensity provided by the light emitting devices can begreater than 3000 μW/cm². For example, the illumination intensity can befrom about 3000 μW/cm² to about 8000 μW/cm².

Unless indicated otherwise herein, illumination intensity values arebased on measurements at the outer surface of molds, and measured usinga Spectronics Corporation digital radiometer DRC-100X with a DIX 365Asensor. This is calibrated by Spectronics Corporation in New York,U.S.A., to NIST standards. The radiometer records integrated intensitybetween the wavelengths of about 320 nm and about 400 nm.

In one embodiment of the invention, the polymerizable composition filledmold is exposed to ultraviolet light, such as substantially consistentultraviolet light, for a period of time sufficient to provide effectivepolymerization of the polymerizable composition, for example, in a rangeof about 5 minutes, or about 15 minutes, or about 30 minutes, to about45 minutes, or about 60 minutes, or about 120 minutes, or longer.Preferably, both the initiation and the termination of the ultravioletlight exposure are rapid or substantially instantaneous, or as close toinstantaneous as possible. The polymerizing light facilitates, or atleast assists in causing, or causes the polymerization of thepolymerizable composition within the mold cavity and the formation of apolymerized article. The present systems and methods attempt to reducethe amount of unpolymerized monomeric components or other unpolymerizedcomponents within the final polymerized article.

In some embodiments, methods comprise exposing the mold or plurality ofmolds to ultraviolet light having an intensity at the surface of themold or plurality of molds in a range of about 100 μW/cm², or about 300μW/cm², or about 500 μW/cm² to about 700 μW/cm², or about 900 μW/cm², orabout 1100 μW/cm² or greater. In other embodiments, the mold orplurality of molds are exposed to an ultraviolet intensity of about 1300μW/cm², or about 1500 μW/cm², or about 2000 μW/cm², or about 3000μW/cm², or about 4000 μW/cm², or about 6000 μW/cm² or about and 8000μW/cm². For example, in certain embodiments, the surface of the mold ormolds is exposed to ultraviolet light having an intensity from about 100μW/cm² to about 2000 μW/cm². These intensities can be determined using aDRC100X radiometer with a Dix 365A sensor. In certain embodiments, amold surface or mold surfaces are exposed to ultraviolet light having anintensity from 50 μW/cm² to 2000 μw/cm². In a preferred embodiment ofthe invention, the mold or plurality of molds, are exposed toultraviolet light having an intensity of no greater than about 400μW/cm² for example, an intensity of about 340 μW/cm². In certainembodiments, the intensity of the light can vary relative to an averageor mean value. For example, the intensity of light can vary by about 50μW/cm². In embodiments where the average UV light intensity is about 340μW/cm², the light intensity can vary by about 15% (e.g., 340±50 μW/cm²).In other embodiments where the average light intensity is about 900μW/cm², the light intensity can vary by about 5% (e.g., 900±50 μW/cm²).The intensity of light emitted by the present systems can vary dependingon the lens precursor composition present in the molds. For example, onesilicon-containing lens precursor composition may require an intensityof about 900 μW/cm², whereas another different silicon-containingcomposition may only require an intensity of about 340 μW/cm². Incertain of the present silicone hydrogel materials, exposure toultraviolet light less than 50 μW/cm² or more than 2000 μW/cm² does notproduce acceptable silicone hydrogel contact lenses. In other words,these silicone hydrogel materials can only be polymerized intoacceptable silicone hydrogel contact lenses if the ultraviolet lightintensity at a mold surface is between 50 μW/cm² and 2000 μW/cm². Theintensities can be chosen empirically taking into consideration factorssuch as properties of the initiator, if any, and the monomericcomponents of the lens precursor composition.

In another broad aspect of the invention, systems are provided forpolymerizing or curing a polymerizable composition by applying lightenergy to a plurality of molds containing the polymerizable composition.For example, systems are provided for polymerizing a polymerizablecomposition, held in a plurality of molds, to form a plurality ofophthalmic lenses therefrom. Each of the molds is preferably configuredto impart a desired shape of an ophthalmic lens for example, a contactlens, to the composition, upon polymerization of the polymerizablecomposition.

In one aspect of the invention, the systems are structured and designedto provide a substantially consistent, more preferably a substantiallyuniform, dose or amount or intensity of light, preferably ultravioletlight, to a plurality of filled molds in a manner such that each one ofthe filled molds is exposed to substantially the same polymerizingradiation as each of the other molds. The systems are designed to enablelarge scale production of lenses, for example, contact lenses. Thepresent systems can be used in the manufacture of a relatively largenumber of contact lenses having uniform, consistent, and/or reproduciblequality.

In one embodiment of the invention, systems are provided which generallycomprise a housing having a chamber, an inlet, and an outlet; and a trayconfigured to hold a plurality of molds, wherein each mold includes alens shaped cavity that contains a polymerizable composition. The trayis movable through the chamber in the housing from the inlet to theoutlet.

The systems further comprise a source of light, for example, a source ofultraviolet light, for illuminating the chamber in order to providepolymerizing radiation to the molds therein and the polymerizablecomposition contained in the molds. For example, the source of light maycomprise a plurality of light emitting elements or lamps structuredand/or positioned to illuminate the housing chamber.

The present systems are particularly useful for the manufacture ofcontact lenses, for example, silicone hydrogel contact lenses or contactlenses that comprise a silicone hydrogel material, including extendedwear and daily wear contact lenses. Each mold may comprise a first moldsection and a second mold section which, when assembled together, form acontact lens shaped cavity therebetween. A polymerizable composition islocated within and can fill the cavity. The polymerizable compositionmay be understood to be a contact lens precursor material, for example,a silicon-containing monomer composition that polymerizes upon exposureto ultraviolet light to form a silicone hydrogel polymeric composition.

In another aspect of the invention, systems are provided which comprisea light assembly, for example, a light assembly comprising a first lightsource for radiating light toward or onto a first surface of a tray, thefirst surface of the tray supporting a plurality of mold assemblies, anda second light source, for radiating light toward or onto asubstantially opposing second surface of the tray from which the moldassemblies extend beyond. Advantageously, the system is preferablystructured such that each of the molds carried by the tray is exposed tolight, for example, ultraviolet light, radiated from both the firstlight source and the second light source.

Each of the first light source and the second light source may comprisea plurality of light sources, for example, a plurality of light emittingelements, for example, a plurality of ultraviolet light emittingelements, such as lamps, tubes and the like, mounted within the housing.For example, the first light source may comprise a plurality ofultraviolet lamps spaced apart from an upper surface of the tray andpositioned to provide light to the upper surface of the tray. Similarlythe second light source may comprise a plurality of ultraviolet lampsspaced apart from a lower surface of the tray and positioned to providelight to the lower surface of the tray. Advantageously, the molds heldin the tray are exposed to ultraviolet radiation from both above andbelow the molds.

In order to provide maximum exposure to both top and bottom majorsurfaces of each of the molds, the tray may include a plurality ofapertures or through holes, each of the apertures being sized andconfigured to allow a single mold, or portion thereof, to be seatedwithin the aperture, with top and bottom major surfaces of each of themolds being not substantially covered or concealed by the tray.

The system may further comprise a transport means or assembly, forexample, a conveyor assembly, for moving or transporting the tray andmolds carried thereby through the housing chamber, for example, duringthe polymerization process. It is desirable that during thepolymerization process, the molds are substantially consistentlyilluminated with substantially consistent, or even substantiallyuniform, intensity, and advantageously are not substantially shadowed orshielded by any components of the conveyor assembly. For example, theconveyor assembly may comprise a moving edge conveyor, for example,including a pair of opposing tracks or belts for accommodating opposingperipheral edge portions of the tray, for example, the mold-filled tray.

In one aspect of the invention, the conveyor assembly is positioned andstructured so as to provide substantially consistent, substantiallyuniform illumination intensity to each of the molds being transportedthereby. For example, the system is structured to minimize or reduce theeffects of shielding the molds from ultraviolet light when the moldingassemblies pass through the illuminated chamber.

In accordance with one aspect of the invention, the conveyor assemblymay be mounted in or to the housing by means of a support structure orsupport structures in such a manner so as to provide substantialconsistency and substantial uniformity of exposure of the molds toeffective amounts of light or polymerizing radiation. For example, insome embodiments of the invention, the support structure includesstructure which holds the conveyor belt or belts away from any of themain support structures of the conveyor assembly so as to position themolds on the tray away from any shadowing by the main supportstructures.

In some embodiments of the invention, there are four support elementswhich together hold the conveyor belt or belts away from any shadowingeffects caused by the conveyor support. For example, in oneconfiguration, the support structure comprises a first structuralelement secured to the housing, and a first outrigger element secured tothe first structural element and extending away from and substantiallyperpendicular to the first structural element. In addition, there isincluded a second support element secured to the first outrigger elementand substantially parallel with the first structural element, and asecond outrigger element secured to the second structural element andextending away from the second structural element and substantiallyperpendicular thereto. The first and second outrigger elements aresubstantially parallel to each other and provide a structure forsupporting the conveyor in a position somewhat away from the edges ofthe system where there is an increased risk of shadowing occurring.

In another aspect of the invention, the present systems includeassemblies for providing a substantially instantaneous start and/or asubstantially instantaneous end or finish to exposing the molds andpolymerizable compositions contained therein to effective amounts oflight. Various structures may be employed to achieve such starts and/orends or finishes.

The system may include structure effective to shield or block themold-filled tray from being prematurely exposed to effective light,meaning, light having an intensity effective to initiate or causepolymerization of the polymerizable composition in the molds.

For example, in some embodiments of the present invention, a UV-lightguarded inlet vestibule is provided for containing or holding newlyfilled molds in a tray prior to the tray being placed in the illuminatedchamber. The inlet vestibule may be located directly adjacent theentrance of the chamber. In addition, a UV light shield may be providedfor substantially preventing UV light from entering the inlet vestibulefrom the illuminated chamber. The light shield may be in the form of agate, for example, a movable, pneumatic gate that is normally closed andis opened, for example, automatically opened, when the mold filled trayis moved from the inlet vestibule into the light chamber.

An outlet vestibule, similar to or identical to the inlet vestibule, canbe provided adjacent the exit of the illuminated chamber for holding amold filled tray immediately after the polymerization process. Like theinlet vestibule, the outlet vestibule may include a pneumatic gate thatis normally closed and can be automatically opened when the tray ismoved from the light tunnel into the outlet vestibule.

Additional or alternative elements, structures and/or mechanisms may beprovided for substantially eliminating or at least reducing occurrenceof UV exposure of the filled molds before the molds are placed on thelight tunnel and after the molds have been cured in the light tunnel.For example, rather than the vestibules described hereinabove, theilluminated chamber inlet may be structured in the form of an inwardlyextending slot, hereinafter sometimes referred to as a “letter-box”inlet or opening. For example, the inlet to the light tunnel may bedefined by a slot having inwardly extending upper and lower panels,shields or other structures, the slot being sized to hold at least onemold-filled tray therebetween.

In embodiments of the invention employing the letter box inlet, one ormore, preferably at least two light emitting elements are disposedimmediately above and below the inwardly extending structure in order toenhance consistency of illumination intensity within the light tunnelduring the entrance and exit of the mold assemblies.

A substantially identical outlet portion having a letter-box typestructure may be provided within the housing. In order to furthermaintain substantially consistent, advantageously substantially uniform,illumination intensity within the housing chamber, at least one opticalsurface may be provided for reflecting and/or diffusing light in thechamber.

In some embodiments of the invention, the optical surface may comprise areflective material and/or a substantially non-reflective materialdisposed on, for example painted on, one or more interior walls of thechamber housing. The optical surface preferably is structured and/orpositioned with respect to the light source so as to reflect light, forexample, ultraviolet light, in a manner that will enhance thepolymerization process for example, by providing an enhanced degree ofconsistent illumination to the molds.

Advantageously, in some embodiments of the invention, optical surfacesare provided having a plurality of different reflectivities. Byappropriate selection of high reflectivity surfaces and/or lowreflectivity surfaces, or a combination thereof, substantially optimumcure conditions in the housing can be achieved. In other words, theoptical surfaces, in conjunction with the light emitting element(s) canbe used as a means of causing light provided to the molds to besubstantially uniform across all of the molds.

In some embodiments of the invention, the system comprises a pluralityof different optical surfaces providing different degrees ofreflectivity, the optical surfaces being effectively positioned in thehousing to cause substantially uniform distribution of light oversurfaces of the tray and molds carried thereby. The plurality of opticalsurfaces are preferably effective to increase uniformity of lightprovided to the tray or trays and molds carried thereby, relative to anidentical system having less than a plurality of optical surfaces forexample a system having an optical surface having only a singlereflectivity.

For example, the plurality of optical surfaces may include a firstoptical surface having a first reflectivity, a second optical surfacehaving a second reflectivity that is greater than the firstreflectivity. In some embodiments, a third optical surface having athird reflectivity greater than the second reflectivity may be provided.

More specifically, the first optical surface may be about 0% and about30% reflective and the second optical surface may be between about 10%reflective and about 50% reflective, of the light emitted from the lightsource.

In a particular embodiment of the invention, the first optical surfaceis about 0% reflective and the second optical surface is about 30%reflective. For example, the first optical surface may be a Matt Blacksurface and the second optical surface may be a Matt Gray surface.

If desirable for enhancing uniform distribution of light, a thirdoptical surface comprising a reflective aluminum or the like may beprovided.

In another aspect of the invention, the optical surface or opticalsurfaces are effective to provide enhanced control over the distributionof light within the chamber, relative to a chamber not including opticalsurfaces. The optical surfaces are used to provide optimum cureconditions by causing each and every one of the molds and thepolymerizable compositions contained therein to be exposed to asubstantially consistent, preferably substantially uniform distributionof light preferably having a substantially optimal cure intensity,during the cure period.

Various structures may be employed to provide the optical surfaces. Forexample, reflective elements may be provided at locations within thehousing that are effective to achieve substantially uniform distributionof light. The optical surfaces having the desired reflectivity maycomprise one or more materials selected from metallic materials, forexample, aluminum or aluminum-containing materials, paints, for example,Matt Black, Matt Gray, opaque, translucent or the like, polishes, and/orany other suitable material that can provide a desired degree ofreflectivity when placed in the chamber.

In a more specific aspect of the invention, the optical surfaces areutilized to compensate for non-uniform light emitted from a lightsource, for example a light source comprising an assembly of ultravioletlamps, for example, ultraviolet fluorescent tubes. As mentionedelsewhere herein, fluorescent tubes are useful in the present inventionfor supplying effective light for polymerizing or initiatingpolymerization of compositions in the mold assemblies. Fluorescent tubestypically tend to have regions of high intensity and regions of lowintensity light. Typically, fluorescent tubes produce lower intensitylight at the end portions of the tubes, and relatively higher intensityof light at the central portions of the tubes. For this reason, when thelight source of the system of the invention is an assembly ofultraviolet lamps, it is desirable to position one or more opticalsurfaces having relatively high reflectivity adjacent end portions ofthe lamps in order to increase illumination intensity to molds locatedor passing adjacent the tube end portions.

In another aspect of the invention, a plurality of optical surfaces areprovided wherein one or more of the optical surfaces are spaced apartfrom the ultraviolet light source at different distances relative to oneor more other of the reflecting elements. For example, in order toincrease illumination intensity at or near end portions of thefluorescent tube, optical surfaces may be placed closer to the endportions relative to the optical surface or surfaces which are placed toreflect light from the central portion of the fluorescent tubes.

In yet another aspect of the present invention, the present systemspreferably include features which are directed at minimizing lensdistortion and/or improving edge shape of the finished lens. Forexample, the systems may be structured such that the first light sourceilluminates one surface of the tray, and filled molds, with light havinga first intensity, and the second light source illuminates the opposingsurface of the tray, and filled molds, with light having a secondintensity that is different from the first intensity.

Advantageously, the first and second intensities of the first and secondlight sources respectively, are selected to achieve a reduced distortionand/or an improved edge shape of the lenses formed from thepolymerizable composition contained in the plurality of molds afterpolymerization of the composition. For example, in one embodiment of theinvention, the top surfaces of the tray, and filled molds, are exposedto ultraviolet light at a first intensity and the bottom surfaces of thetray and filled molds are exposed to ultraviolet light at a secondintensity, wherein the second illumination intensity is less than, orreduced relative to, the first illumination intensity.

In another aspect of the present invention, the system is structured soas to maintain a desired temperature within the housing. In a preferredembodiment of the present invention, the desired temperature maintainedwithin the housing, for example, within the chamber of the housing, isbetween about 15 degrees C. or about 20 degrees C. to about 30 degreesC. or about 35 degrees C. In one embodiment, the desired temperaturewithin the housing is substantially maintained at about 25 degrees C.Effective maintenance of temperature may be accomplished by utilizationof temperature sensors and/or cooling devices implemented into thesystem. Preferably, the system is designed to effect polymerization orcuring of the polymerizable composition by light energy, for example,ultraviolet light energy, without any substantial heat-inducedpolymerization of the composition.

In one aspect of the invention, devices for monitoring light intensitywithin the chamber are provided. For example, remote data loggers,capable of sensing and recording light intensity, may be placed atvarious positions on one or more of the trays while the trays are beingconveyed through the chamber.

In yet another aspect of the invention, the present systems includedetection means or assemblies for detecting failure of individual lightsources. Preferably, such assemblies include an electronic ballastconnected to a pair of light emitting elements and a control assemblythat utilizes DALI protocol-based technology to identify and alert anoperator to lamp failure.

Each and every feature described herein, and each and every combinationof two or more of such features, is included within the scope of thepresent invention provided such feature included in such combination arenot mutually inconsistent. In addition, any feature or combination offeatures may be specifically excluded from any embodiment of the presentinvention.

These and other aspects of the present invention are apparent in thefollowing detailed description and claims, particularly when consideredin conjunction with the accompanying drawings in which like parts bearlike reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified cross-sectional view of a mold useful for forminga contact lens.

FIG. 1A is a cross-sectional view of the mold of FIG. 1 having apolymerizable composition disposed therein and being located in a trayuseful in a system of the invention.

FIG. 2 is a perspective partially cut-away view of a system inaccordance with the invention, the system being useful in practicingsome of the methods of the present invention, and generally including ahousing, a source of polymerizing radiation, and a conveyor assembly.

FIG. 3 is a cross-sectional view of the system shown in FIG. 2.

FIG. 4 is a cross-sectional view similar to the cross-sectional viewFIG. 3, of another system in accordance with the invention, wherein thesystem includes optical surfaces spaced apart at different distancesfrom the light source in order to enhance consistency of illuminationintensity in the housing chamber.

FIG. 4A is a diagram of illumination intensity values at surfaces of aplurality of molds spaced apart from an ultraviolet lamp, and theintensity of the lamp is set at 500 μW/cm² and an optical surface isprovided above the lamp which comprises a single reflectivity.

FIG. 4B is a diagram similar to FIG. 4A, except that the optical surfacecomprises two different reflectivities.

FIG. 4C is a diagram similar to FIG. 4B except that the optical surfacecomprises two other reflectivities.

FIG. 4D is a simplified cross-sectional view of an advantageousembodiment of the invention having optical surfaces with differentreflectivities.

FIG. 4D′ is a plan view of an optical surface taken along line 4D′-4D′in FIG. 4D.

FIG. 4E is a side view of a portion of the system shown in FIG. 4D,showing a reflector having slots for receiving end portions of UV lamps.

FIG. 5 is another cross-sectional view of the system shown in FIG. 2,illustrating a “letter-box” style inlet for shielding the molds, andpolymerizable composition therein, from experiencing regions ofillumination intensity less than the desired illumination intensity.

FIG. 6 is a top view of the system shown in FIG. 2, with a portion ofthe housing removed in order to more clearly show alignment of theultraviolet lamps and a conveyor assembly structured to move a traythrough the housing chamber and a fast-drag mechanism for at leastassisting in effecting substantially instantaneous illumination ofeffective light to the molds.

FIG. 7A is a diagram showing illumination intensities at mold surfacesas measured at different distances along the conveyor assembly beneaththe first three lamps in a system of the present invention.

FIG. 7B is a diagram showing an advantage of providing the “letter-box”style inlet shown in FIG. 5.

FIG. 8 shows conveyor assembly support structure that optimizesillumination intensity in the housing chamber by reducing occurrence ofshadows or shielding by components of the conveyor assembly.

FIG. 8A shows a top plan view of an arrangement of light sensors usefulfor measuring and/or monitoring intensity of light in the systems of theinvention during processing of lenses.

FIG. 8B shows a diagrammatical view of multiple tracks monitored by thelight sensor arrangement shown in FIG. 8A.

FIG. 9 shows a diagram of a preferred lighting control system utilizingDALI protocol-based technology in accordance with the present invention.

FIG. 10 shows a cross-sectional view of another system of the presentinvention.

FIG. 11 is a perspective view of another embodiment of the presentsystems.

DETAILED DESCRIPTION

The present invention will typically be described herein with respect tomethods and systems useful for the manufacture of contact lenses, thoughit is to be appreciated that, with appropriate modification thereto, thepresent methods and systems may be useful for the manufacture of othertypes of ophthalmic lenses and other light-polymerizable articles ingeneral.

The following documents are incorporated by reference in theirentireties: Martin et al., U.S. Pat. No. 5,597,519; Galas, U.S. Pat. No.5,759,318; Grouev et al, U.S. Pat. No. 6,333,605; Lai, U.S. Pat. No.6,359,024; Lai, U.S. Pat. No. 6,465,538; Iwata et al., U.S. PatentPublication No. 2002/0016383; Heinrich et al., U.S. Patent PublicationNo. 2003/0090014; European Patent Application No. EP 1 314 527; andEuropean Patent Application Publication No. 0 686 484.

The term “contact lens” as used herein refers to an ophthalmic lenswhich, after its removal from a mold in which it is made, is of astructure, size, shape and power that it can be worn on the cornea of aneye. The term “contact lens” can also be understood to refer to anarticle which upon removal from a mold needs to be treated, for example,hydrated and swelled into a lens of size, shape and power as to bewearable on an eye.

Preferably, the contact lens is a hydrogel-containing lens, morepreferably a silicone hydrogel-containing lens.

In a broad aspect of the invention, methods of manufacturing ophthalmiclenses, for example but not limited to soft silicone hydrogel lenses,are provided. The methods generally comprise providing a mold assembly2, such as the mold assembly 2 shown in cross sectional view in FIG. 1.The mold assembly 2 may comprise a lens mold, including a first moldsection 3 having a first lens defining surface 4 and a second moldsection 5 having a second lens defining surface 6. The first and secondmold sections 3 and 5 define a lens shaped cavity 8 between the firstand second lens defining surfaces 4 and 6 when the first mold section 3and the second mold section 5 are assembled together.

Turning now to FIG. 1A, a polymerizable composition 9 is provided in thelens shaped cavity 8. The polymerizable composition 9 can be understoodto be a lens precursor composition. The polymerizable composition 9 canbe a composition comprising one or more monomeric components suitablefor producing contact lenses. The polymerizable composition 9 can beprovided in the lens shaped cavity 8 by a number of different methods,for example, by injecting, dispensing, or otherwise introducing apolymerizable composition 9 into the lens shaped cavity.

Ophthalmic lenses manufactured using the present systems and methods mayinclude ophthalmic lenses made from biocompatible, non-hydrogelmaterials or components. Examples of non-hydrogel materials include, andare not limited to, acrylic polymers, polyolefins, fluoropolymers,silicones, styrenic polymers, vinyl polymers, polyesters, polyurethanes,polycarbonates, cellulosics, proteins including collagen-based materialsand the like and mixtures thereof.

Preferably, for the manufacture of contact lenses in accordance with thepresent invention, the polymerizable composition comprises a formulationcomprising one or more silicon-containing monomers and/orsilicone-containing macromers.

A preferred polymerizable composition for the manufacture of siliconehydrogel lenses that is suitable for use in the systems and methods ofthe present invention is described in PCT Publication No. WO2006026474,which is hereby incorporated by reference in its entirety. Thepolymerizable composition may include components such as a tintcomponent, a UV blocker component, and/or the like.

A method of the present invention may comprise a step of exposing theclosed mold assembly 2 to polymerizing initiating radiation, preferably,in the form of ultraviolet light, in order to initiate and causepolymerization of the polymerizable composition 9 in the mold assembly2. The step of exposing includes providing an effective amount of lightto the mold assembly 2 that will cause complete polymerization of thepolymerizable composition within the mold.

In one embodiment, the polymerizable composition 9 is effectivelypolymerized by a method including a step of exposing the composition,for example, exposing the mold assembly 2 and the polymerizablecomposition 9 therein, to light in the ultraviolet spectrum having anillumination intensity of between about 100 μW/cm² or about 200 μW/cm²or about 300 μW/cm² and about 900 μW/cm² or about 1000 μW/cm² or about2000 μW/cm². More preferably, the polymerizable composition 9 iseffectively polymerized, for example, substantially completelypolymerized, by exposing the mold assembly 2 and the polymerizablecomposition 9 therein, to light, for example, light in the ultravioletspectrum having an illumination intensity of between about 200 μW/cm²and about 1000 μW/cm², and more preferably, no greater than about 400μW/cm².

It is to be appreciated that visible light initiators and/or other formsof light energy may additionally or alternately be employed within thescope of the present invention. Such initiators and/or other forms oflight energy and corresponding appropriate modifications to the methodsand systems described herein will be known to those of skill in the artand are considered to be within the scope of the present invention.

Unless expressly indicated otherwise herein, the illumination intensityvalues provided in the present detailed description refer to theillumination intensity occurring at an outer surface of the mold, asdistinguished from the intensity of the light occurring within thepolymerizable composition within the mold. In addition, unless expresslyindicated otherwise herein, the values of illumination intensityprovided in the present description are values obtained or obtainablewhen the intensity is measured using light sensors, such as aSpectronics Corporation digital radiometer DRC 100X with a DIX 365Asensor. This is calibrated by Spectronics Corporation located in NewYork, U.S.A., to NIST standards, or equivalent equipment calibration.The radiometer records integrated intensity between the wavelengths of320 nm and 400 nm. For example, digital radiometers from differentsuppliers, and/or radiometers that are calibrated differently or todifferent standards may provide different intensity values.

The mold sections 3 and 5 can be made by any suitable molding techniqueknown in the art.

The mold assembly 2, and preferably, each of the individual moldsections 3 and 5, comprises a suitable material that is at leastpartially transparent to the polymerizable radiation, for example,light, for example, ultraviolet light. By “at least partiallytransparent” is meant herein that some and preferably substantially allradiation having an intensity and/or wavelength effective to initiatepolymerization of the polymerizable composition 9 or to polymerize thepolymerizable composition 9, can pass through the mold portions 3 and 5to polymerize or cure the polymerizable composition 9.

In a preferred embodiment, mold sections 3 and 5 that include, or aremade of, an ethylene vinyl alcohol resin (hereinafter, usually, EVOH)are processed by the present systems and methods. One example of asuitable EVOH polymer or copolymer useful in the present molds isavailable under the trade name, SOARLITE. SOARLITE is associated withhigh mechanical strength, antistatic properties, low contractilityduring molding, oil and solvent resistance, small coefficient of thermalexpansion, good abrasion resistance, and excellent moldingprocessability. Thus, other polymeric materials with one or more similarproperties may be useful in the producing molds useful in the presentsystems.

The mold portions 3 and 5 alternatively may be made of polystyrene orother suitable polymer material so long as the mold portions are atleast partially transparent to the polymerization initiating wavelengthsof light, and so long as the material permits removal of the moldedarticle, for example, the lens, after the polymerization process. Otherexamples of suitable materials for the mold portions 3 and 5 include,but are not limited to, polyvinylchloride, polyethylene, polypropylene,copolymers or mixtures of styrene with acrylonitrile or butadiene,polyacrylonitrile, polyamides, polyesters and the like.

Preferably, the step of exposing comprises exposing the mold andpolymerizable composition therein to a substantially consistent,preferably substantially uniform intensity of light. For example, suchsubstantially consistent exposure is preferable over exposure to lighthaving an intensity that varies during the polymerization period. Inaddition, it has been discovered that substantially optimal cureconditions for example, polymerization, can be achieved when the periodof exposure to the ultraviolet light is substantially instantaneous.

The duration of exposure of the mold assembly to the polymerizingultraviolet light is preferably a continuous period of exposure. Theperiod of exposure, or cure period, is at least sufficiently long tocause substantially complete polymerization of the polymerizablematerial within the cavity, preferably with little or substantially noresidue of unpolymerized material remaining within or on the mold. Theduration of exposure may vary to some degree depending upon factors suchas the specific formulation of the polymerizable composition.

In one embodiment of the invention, the duration of exposure, or periodof exposure, is at least about 5 minutes, or about 10 minutes, or about30 minutes to about 45 minutes, or about 60 minutes, or about 90minutes, or more in length. In some embodiments of the invention, theperiod of exposure is at least about 20 minutes, for example at leastabout 30 minutes, to about one hour with the illumination intensitybeing less than 2000 μW/cm², for example, less than about 900 μW/cm²,for example, less than 400 μW/cm². In a more specific embodiment of theinvention, the cure period is between about 10 minutes and about onehour in length, during which time the mold is exposed to substantiallyconsistent light having an illumination intensity of about 340 μW/cm².

In another aspect of the invention, methods are provided formanufacturing contact lenses by providing a mold assembly having a lensshaped monomer filled cavity therein, and exposing the mold toultraviolet light having an illumination intensity of between about 8μW/cm² to about 400 μW/cm², wherein, in this case, the intensity is theillumination intensity occurring within the monomer-filled lens shapedcavity.

In one embodiment of the present invention, mold assemblies 2 areprovided that are made of EVOH based materials as described in greaterdetail elsewhere herein. The molds and the individual mold sectionsthereof have attenuation values of between about 80% to about 92% ofincident light.

It will be appreciated by those of skill in the art that the intensityof light within the mold, for example the intensity of light at orwithin the polymerizable composition within the mold, depends on theproperties of the mold through which the light must pass.

It has been discovered that when the intensity value at the mold surfaceis a value between about 100 μW/cm² and about 2000 μW/cm², the intensityrange of the ultraviolet light at the interface of the mold and thepolymerizable composition has a value between about 8 μW/cm² and about400 μW/cm².

For example, if the attenuation of the mold is calculated to be betweenabout 80% and about 92% of incident light, an intensity range of 300μW/cm² to 1000 μW/cm² at the mold surface means the intensity value atthe composition/mold section interface is a value within the range ofbetween about 24 μW/cm² and about 200 μW/cm².

For reasons that will be appreciated by those of skill in the art, it isdifficult to directly measure the intensity of the ultraviolet lightoccurring on the polymerizable material within the cavity of the mold.However, the intensity of the light within the cavity can be calculatedif the attenuation of incident light by the mold is known. Generally,the intensity value within the mold cavity is calculatable bymultiplying the intensity value of incident light at the mold surface(which is directly measurable using conventional equipment) by the moldattenuation value, which is provided as a percentage value.

Attenuation of light by the mold depends on many factors such as thecomposition of the mold material, the thickness and shape of the moldpieces, the wavelength and angle of incident light, etc. Measurement ofattenuation values can be accomplished using carefully placed opticfibers and utilizing conventional spectrometer equipment.

The light intensity, for example ultraviolet light intensity, at thesurface of the mold may be measured using a Spectronics CorporationSpectroline integrating radiometer, as discussed herein.

The following description provides a technique for determiningultraviolet intensity within the mold cavity, as compared to theintensity values measured at an exterior surface of the contact lensmold.

As mentioned hereinabove, it should be appreciated that intensity ofultraviolet light inside the monomer filled mold cavity can becalculated based on attenuation of the mold material which is ameasurable value provided in units of percentage. Attenuation ofincident light by the mold can be deducted from known information suchas the type of mold material, the mold thickness, the shape of the mold,the position of the mold beneath the ultraviolet light source, the angleof measurement, and the wavelength of incident light.

Using values for attenuation of ultraviolet light by the mold material,it is possible to estimate the ultraviolet intensity values inside themold cavity. Although theoretically a somewhat simple calculation, inpractice this can be quite a complicated procedure.

The attenuation of incident light having a wavelength of 370 nm througha mold can be calculated as follows. For purposes of illustration, theEVOH mold has the following known or directly measurable parameters.Each EVOH mold section has a substantially continuous mold sectionthickness of about 1.6 mm measured between an outer surface of a moldsection and the lens defining surface thereof. The light source is asingle ultraviolet lamp. Measurement of intensity values are takenthrough a center line of the mold using a measurement fiber,specifically a fiber optic, for example, a 50 μm diameter fiber opticplaced vertically through and into the mold cavity. Intensitymeasurement values are determined using a spectrometer, for example, aStellarNet, Inc. EPP2000 spectrometer. Software, for example, Spectrawizsoftware by StellarNet, Inc., is also used to facilitate thecalculations.

Using these known or directly measurable parameters, the attenuation ofincident light through the mold is calculated to be about 85%. In otherwords, the value of light intensity inside the mold cavity is determinedto be about 15% of the value of the incident light intensity.

It is noted that the intensity of light inside the mold cavity may bedifferent than that described hereinabove when other variables are takeninto account. For example, it is hypothesized that if the light isindirect light rather than direct light, the optic fiber sensor is not“looking” directly at the ultraviolet lamp, and the attenuation may becalculated to be lower. For example, it is believed that if the fiberoptic sensor is recording indirect and scattered light, which can bedescribed as “diffuse” light, the intensity value at the mold cavitywill be affected. For example, using the same parameters as describedhereinabove with the exception being that the fiber optic is not pointeddirectly at the light source, the attenuation of incident light willhave a value of about 20%, such that the light inside the cavity isabout 80% of incident light intensity.

In view of the above, it can be understood that the present inventionincludes methods of making silicone hydrogel contact lenses. Embodimentsof the present methods comprise exposing a contact lens mold comprisinga polymerizable silicone hydrogel lens precursor composition toultraviolet light. The ultraviolet light can have an intensity fromabout 100 μW/cm² to about 2000 μW/cm², for example, between 50 μW/cm²and 2000 μW/cm². With the mold materials used in these embodiments, thepolmerizalbe silicone hydrogel lens precursor composition in the lensshaped cavity of the mold is exposed to an intensity of ultravioletlight from about 8 μW/cm² to about 400 μW/cm², for example, between 5μW/cm² and 400 μW/cm². The intensity of the ultraviolet light within thelens shaped cavity is calculated by multiplying the attenuation factorof the mold material by the actual thickness of the mold. In theseembodiments, with these silicone hydrogel contact lens materials, theultraviolet light intensity must be within these ranges to produce anacceptable silicone hydrogel contact lens.

Quality lens shaped products having minimal or negligible distortion andgood edge shape can be produced using a desired range of intensityvalues provided at an exterior surface of EVOH molds. Suitable ranges ofvalues can be determined as follows.

A number of identical or substantially identical EVOH contact lens moldsare provided having the parameters described above. Each mold is given alabel to identify the illumination intensity to which the particularmold will be exposed. Each mold is labeled with a different, specificultraviolet intensity value, such that there are separately identifiedmolds each labeled with a specific intensity value ranging from 20μW/cm² to 8000 μW/cm².

The lens shaped cavity of each mold is filled with an identical amountof a contact lens precursor material, specifically a silicone hydrogellens precursor composition comprising a polysiloxanyl dimethacrylatesilicone monomer and a polydimethylsiloxane methacrylate derivative.

Each filled mold is placed in an ultraviolet light chamber having adesired illumination intensity. The chamber is illuminated with acontinuous light having a constant illumination intensity. This light isprovided by one or more ultraviolet emitting elements arranged above andbelow the mold. The mold is located about 70 mm spaced apart from theultraviolet emitting elements. In this example, intensities between 20μW/cm² and 1500 μW/cm² were provided by a Philips 20 watt ultravioletflorescent tube. Intensities between 2000 μW/cm² and 8000 μW/cm² areprovided by a 400 watt ultraviolet flood lamp. The lamps can be providedby UV Light Technology Limited, Birmingham, England, B68 OBS. The lampsare connected to control equipment for setting and maintaining thedesired constant illumination intensity in the chamber. The ultravioletintensities are values of integrated intensity between the wavelengthsof about 320 nm to about 400 nm.

Control measurements are provided or can be obtained using a sensormechanism having a sensor head located about 70 mm from the surface ofthe ultraviolet emitting elements for ensuring accuracy of theultraviolet light value at the outer surface of the mold. The intensityvalues at the mold surfaces are measured using Spectroline DigitalRadiometer DRC-100X, Spectroline UVA-Sensor Dix 365A, manufactured bySpectronics Corporation, 956 Brush Hollow Road, Westbury N.Y. 11590.

Each filled mold is exposed to the appropriate intensity value labeledon the mold. More specifically, each mold is exposed to an ultravioletintensity having at least one value selected from the group consistingof 20 μW/cm², 100 μW/cm², 180 μW/cm², 300 μW/cm², 530 μW/cm², 700μW/cm², 900 μW/cm², 1100 μW/cm², 1300 μW/cm², 1500 μW/cm², 2000 μW/cm²,3000 μW/cm², 4000 μW/cm², 6000 μW/cm² and 8000 μW/cm². The duration ofexposure of the molds to the ultraviolet radiation is for an identicalperiod of approximately ten minutes, which causes the monomer in each ofthe cavities to polymerize.

A control mold is also provided. The control mold comprises a closedmold with no lens precursor material in its lens shaped cavity. Thecontrol mold is exposed to ultraviolet light having an intensity of 8000μW/cm² for the same period of exposure as the filled molds, i.e., for aperiod of approximately ten minutes.

After the exposure step, each mold is subjected to a hydration/removalprocess that is typical in the art. A polymerized lens product isthereby obtained and observed.

It is discovered that each of the polymerized lens products formed fromthe materials described above that have been cured with ultravioletlight at intensities about 20 μW/cm² or less, and each of thepolymerized lens products that have been cured with ultraviolet light atintensities of greater than about 4000 μW/cm² all exhibit an undesirablewhite deposit on the surface of the mold. The polymerized lens productsthat have been cured with ultraviolet light at intensities of greaterthan 20 μW/cm² but less than 4000 μW/cm² exhibited no observable whiteresidue. It is noted that these results at least in part relate tospecific formulations of monomeric composition and that the results maybe slightly different for other formulations of monomeric composition. Aperson of ordinary skill in the art, without undue experimentation,could find the intensity effective to achieve the desired curingresults, such as a lack of white residue or other visible residue, basedon a specific formulation of monomeric composition. For example, asdiscussed herein, when ultraviolet light is provided to a mold surfaceat an intensity between 50 μw/cm² and 2000 μw/cm² acceptable siliconehydrogel contact lenses are produced with the present silicone hydrogelmaterials. These lenses do not have a white visible residue. Asdiscussed herein, the light intensity to which the lens material isexposed with such mold surface intensities is between 5 μW/cm² and 400μW/cm².

It is also found that the control mold (intensity value 8000 μW/cm², nolens precursor material in cavity) has no detectable white deposit afterthe exposure to the ultraviolet light.

Although not intending to be bound by or limited to any particulartheory of operation, it is believed that the white deposit on the moldshas been created by a polymerization reaction between hot water in thehydration step and residual precursor material or unreacted monomericcomponents which was not polymerized during the ultraviolet lightexposure period. This theory would explain the absence of the whiteresidue on the control mold. Thus it is believed that the white depositon those molds exposed to about 20 μW/cm² or less, and those moldsexposed to more than 4000 μW/cm² is due to the lens precursor materialcomposition in the lens shaped cavity, and not the mold material itself.

This “white residue” is generally undesirable as it tends to create arough surface on the contact lens. It is also believed that the presenceof the white residue indicates that the contact lens product did noteffectively and/or thoroughly polymerize within the mold cavity duringthe exposure to the ultraviolet light. It can be hypothesized that thepresence of the white residual material indicates that there is lesspolymerized material incorporated into these lens products relative tothose lens products showing no white residue. The lens products thathave not thoroughly, or otherwise not effectively, polymerized willlikely have characteristics, for example, swelling, that are differentthan those desirable characteristics.

In another aspect of the invention, the methods are designed to providepolymerizing radiation to the lens precursor material in the molds,without any significant addition of heat thereto. More specifically, itis preferred that no significant heat is involved in causing thepolymerization of the lens product, only light energy.

For example, in one embodiment of the invention, the method ofmanufacturing ophthalmic lenses further comprises maintaining a curetemperature at between about 20 degrees C. and about 30 degrees C., forexample about 25 degrees C. For example, this aspect of the inventionmay comprise steps directed at curing the contact lens precursormaterial by exposing the filled mold to ultraviolet light provided by anultraviolet box comprising a substantially enclosed housing havingultraviolet emitting elements therein. The step of exposing is performedwhile the housing is maintained within the desired temperature range,for example using temperature sensors, cooling mechanisms and/or othermeans for maintaining the desired temperature within the housing.

Alternatively, the present methods can be practiced at room temperaturewithout any temperature controllers. For example, successful curing ofthe lens precursor composition can be obtained at temperatures betweenabout 20° C. and about 25° C., for example about 22° C. However,successful curing of the lens precursor compositions can occur attemperatures less than 20° C., such as 14° C.

In yet another aspect of the invention, the step of exposing the mold toultraviolet light may comprise exposing both a first surface and asubstantially opposing second surface of the mold to ultraviolet light.More specifically, the method includes radiating polymerizing radiationonto both a top surface of the mold, and substantially simultaneouslyradiating polymerizable radiation onto a bottom surface of the mold.This may be accomplished, for example, by providing an upper ultravioletlight source spaced apart from the top surface of the mold, and a lowerultraviolet light source spaced apart from a bottom surface of the mold.

For example, in one embodiment of the present invention, an ultravioletlight box or housing having an illuminated chamber may be providedwherein the light box is structured to receive a plurality of suchmolds. Preferred embodiments of suitable ultraviolet light boxes, inaccordance with the present invention, are described in greater detailelsewhere herein. Generally however, for purposes of performing themethods of the present invention, a light box is provided which isequipped with a first set of light emitting elements and a substantiallyopposing second set of light emitting elements. The molds may bepositioned between the first and second sets of light emitting elementsby means of a suitable tray, rack or carrier structured to be placedinto the light box between the first and second set of light emittingelements.

In a more specific aspect of the invention, the method includes placingthe molds in a tray having a plurality of through holes, or apertures,each aperture being sized and configured to allow a mold to be removablyseated therein. This arrangement allows optimal exposure of theplurality of filled molding assemblies to the ultraviolet radiation fromboth an upper source of ultraviolet light and a lower source ofultraviolet light. Thus, the molds can be readily placed in theultraviolet light box in a manner that exposes the top and bottomsurfaces of the molding assemblies to light which provides effectivecuring of the monomer composition.

In a related aspect of the invention, the method of manufacturingophthalmic lenses includes exposing a first surface of the mold or moldassembly to ultraviolet light having a first illumination intensity andexposing a second substantially opposing surface of the mold toultraviolet light having a second, different intensity. The method maycomprise exposing different surfaces of the mold to differentillumination intensities of ultraviolet light, wherein the intensitiesare selected so as to achieve reduced distortion, for example, moredesirable edge shape, of the polymerized lens shaped product, relativeto a lens shaped product produced using a substantially identical methodwithout utilizing different illumination intensities.

It is an object of the invention to achieve a lens product having areduced distortion, for example, an ovality of no greater than about0.04 mm.

For example, in one embodiment of the invention, the top surface of themold is exposed to ultraviolet light having a first illuminationintensity and the bottom surface of the mold is exposed to ultravioletlight having a second illumination intensity that is less than the firstillumination intensity. In a more specific embodiment of the invention,the first illumination intensity is about 400 μW/cm² and the secondillumination intensity is in a range from between about 100 μW/cm², orabout 150 μW/cm² to less than about 300 μW/cm² or less than about 400μW/cm². In another related embodiment of the invention, thepolymerizable composition includes an ultraviolet blocker component andthe second illumination intensity is less than the first illuminationintensity.

Lens measurements from various trials during the development of thepresent systems and methods, are shown as the following Table 1 to Table6. These Tables illustrate how the different settings of upper and lowerlamp intensity influence lens distortion and edge shape. The data inTable 1 to Table 6 were obtained using a monomeric composition includingan ultraviolet blocker component.

Lens distortion is measured as both ovality and distortion of a stripsample of monomer material. It has been discovered that there areintensity settings which minimize ovality e.g., ovality of no greaterthan about 0.04 mm and create good edge shape.

TABLE 1 Material A. Lens ovality versus upper and lower lamp settings.Upper lamp Lower lamp Average lens Intensity intensity ovality μW/cm²μW/cm² mm 400 400 0.15 400 230 0.07 400 150 0.05

TABLE 2 Material B. Lens ovality versus upper and lower lamp settings.Upper lamp Lower lamp Average lens Intensity intensity ovality μW/cm²μW/cm² mm 400 400 0.73 400 320 0.08 400 230 0.04 400 150 0.04

TABLE 3 Material A. Distortion of strip sample versus upper and lowerlamp settings. Width of Upper lamp Lower lamp Lens unsupported lensIntensity intensity Diameter cross section Difference μW/cm² μW/cm² mmmm mm 400 400 13.03 11.14 −1.89 400 230 13.30 13.29 −0.01 400 150 13.4514.93 1.48

TABLE 4 Material B. Distortion of strip sample versus upper and lowerlamp settings. Width of Upper lamp Lower lamp Lens unsupported lensIntensity intensity Diameter cross section Difference μW/cm² μW/cm² mmmm mm 400 400 13.27 11.08 −2.19 400 320 13.21 11.47 −1.74 400 230 13.3112.78 −0.53 400 150 13.44 14.36 0.92

TABLE 5 Material A. Edge shape versus upper and lower lamp settings.Upper lamp Lower lamp Intensity intensity Edge μW/cm² μW/cm² Shape 400400 good 400 230 slight flare 400 150 flare

TABLE 6 Material B. Edge shape versus upper and lower lamp settings.Upper lamp Lower lamp Intensity intensity Edge μW/cm² μW/cm² Shape 400400 good 400 320 good 400 230 slight flare 400 150 flare

Thus, in some embodiments of the present invention, the step of exposingincludes exposing a top surface of the mold to a first intensity ofpolymerizing light and simultaneous therewith, exposing a bottom surfaceof the mold to a second intensity of polymerizing light wherein thesecond intensity is different from the first intensity.

Turning now to FIG. 2, a system in accordance with the present inventionfor producing articles for example, ophthalmic lenses, for example,contact lenses, by means of light-induced polymerization ofpolymerizable compositions is generally shown at 10. The system 10 isespecially useful in performing at least some of the methods of thepresent invention described elsewhere herein.

The system 10 may be structured to provide polymerizing radiation, inthe form of light, for example ultraviolet light, to a mold assembly 2such as shown in FIG. 1A, containing a polymerizable composition 9, forexample, a lens precursor material.

The system 10 generally includes a housing 12 having a chamber 14, aninlet portion 16, an outlet portion 18, and a tray 24 (also shown inFIG. 1A) structured to be positioned within the housing chamber 14 andmovable between the inlet portion 16 and the outlet portion 18. The tray24 is configured to hold or carry a plurality of molds or moldassemblies 2, wherein each mold assembly 2 contains a polymerizablecomposition described elsewhere herein. In the embodiment shown in FIG.2, system 10 is structured to accommodate two trays 24 in a side by sideposition, each tray 24 being structured to hold 256 molds. In otherembodiments of the invention systems are provided that are structured tohold only one tray, or more than two trays, each of the trays beingstructured to hold any number of molds.

Turning back briefly to FIG. 1A, each mold assembly 2 is held within asuitably configured aperture or through hole 30 defined within the tray24. For example, the tray 24 includes a plurality of through holes 30,each of the through holes 30 being sized and configured to allow a moldassembly 2 carried by the tray 24 to be seated therein. Each moldassembly 2 may be held with a concave exterior surface 32, or topsurface, of the first mold portion 3 facing upward and a convex exteriorsurface 34, or bottom surface, of the second mold portion 5 facingdownward.

In accordance with the present invention, the molds 2 further include aquantity of a polymerizable composition 9 located within in the lensshaped cavity and preferably completely filling the lens shaped cavity.

The polymerizable composition preferably comprises a composition thatpolymerizes, for example substantially completely polymerizes, whenexposed to light, for example ultraviolet light, for example, very lowintensities of ultraviolet light, as described in greater detailelsewhere herein. The polymerizable composition may include componentssuch as a tint component, a UV blocker component, and/or the like. Incertain embodiments, the composition is free of a UV blocker component.Polymerizable compositions that are especially useful with the systemsof the present invention include the compositions described in PCTPublication No. WO2006026474.

Turning now as well to FIG. 3, the system 10 further comprises a sourceof polymerizing radiation, preferably light, for example, ultravioletlight, effective to facilitate, for example initiate, polymerization ofthe polymerizable composition within the molds 2.

In the system 10 shown in FIG. 3, the source of polymerizing radiationcomprises a light assembly 50 located in the housing 12 and structuredto illuminate a first side of the tray and a substantial opposing secondside of the tray with light having an intensity effective to facilitatepolymerization of the polymerizable composition. The light assembly 50comprises, for example, a plurality of light sources, for example, afirst light source 50 a located in the housing 12 and spaced apart froma first side of the tray 24, and a second light source 50 b, spacedapart from a substantially opposing second side of the tray 24.

The system 10 is advantageously structured to expose all of the molds ormold assemblies 2 arranged on or in the tray 24 to light having anintensity effective to initiate polymerization and/or causepolymerization, for example, substantially complete polymerization, ofthe polymerizable composition in the molds 2.

In some systems of the present invention, the intensity of thepolymerizing light at the surfaces of the tray 24 and molds 2 carriedtherein is no greater than about 2000 μW/cm². For example, thepolymerizing light comprises ultraviolet light having an intensity atthe surface of the tray and the molds in a range of about 100 μW/cm², orabout 300 μW/cm², or about 500 μW/cm² to about 700 μW/cm², or about 900μW/cm², or about 1100 μW/cm². In other embodiments of the invention, thepolymerizing light comprises ultraviolet light having an intensity ofabout 1300 μW/cm², or about 1500 μW/cm², or about 2000 μW/cm², or about3000 μW/cm², or about 4000 μW/cm², or about 6000 μW/cm² or about and8000 μW/cm². In some embodiments of the present invention, thepolymerizing light comprises ultraviolet light having an intensity of nogreater than about 400 μW/cm² for example, an intensity of about 340μW/cm².

In an especially advantageous embodiment of the invention, thepolymerizing radiation provided by the first and second light sources 50a and 50 b are structured to be effective to cause polymerization,preferably substantially complete polymerization, of substantially allof the 256 molds located in the trays 24.

Advantageously, the system 10 is structured so that the polymerizinglight provided to the trays and molds carried therein is an amount thatis effective to cause substantially complete polymerization of thecomposition in the molds. Preferably, the polymerizing light provided tothe trays and molds carried therein is an amount that is less than anamount that would cause negative structural effects on the polymerizedlens due to excessive lens remaining exposed to the effective light forlonger than is optimal.

Still referring to FIGS. 2 and 3, each of the first light sources 50 aand 50 b may comprise ultraviolet light emitting elements, for examplecolumnated lamps or UV tubes 54, arranged substantially parallel to oneanother along a length of the system 10. In a specific embodiment of theinvention, each of the first light source 50 a and the second lightsource 50 b comprises between about 6 or about 10 and about 80 or about100 or more individual lamps 54. For example, in one especiallyadvantageous embodiment, each of the first and second light source 50 aand 50 b comprises about 40 lamps. Each lamp 54 may comprise, forexample, an ultraviolet fluorescent lamp 54, for example, a 40 wattultraviolet fluorescent lamp 54. Each lamp 54 may be a standard lengthlamp, for example, each lamp may be about 1.20 meters in length.

Preferably, the system 10 is structured such that both the first (e.g.top) surface and the second (e.g. bottom) surface of the tray 24 and themolds 2 carried therein, are exposed to polymerizing light during thepolymerization process. In other embodiments of the invention, only thetop surface, or alternately, only the bottom surface, of the tray ortrays 24 is exposed to polymerizing light during the polymerizationprocess.

The light assembly 50 is preferably connected to an electrical controlmeans (not shown) for supplying suitable electric current to the lamps54.

Turning now specifically to FIG. 3, the system 10 preferably includes aconveyor assembly 70 structured to move or transport the tray 24 throughthe housing 12. The conveyor assembly 70 may comprise any suitablemechanism for moving the tray 24 through the chamber 14 and between thefirst and second light sources 50 a and 50 b. The conveyor assembly 70moves the tray or trays 24 from the inlet portion 16 to the outletportion 18 of the housing 12 while the chamber 14 is illuminated by thelight source 50, preferably by entirely all of the lamps 54 of the lightsource 50. Preferably, the conveyor assembly 70 and light assembly 50are structured so as to provide substantially consistent, substantiallyuniform illumination to both top and bottom surfaces of the tray ortrays 24 and preferably to top and bottom surfaces of each and every oneof the molds 2 held in the tray or trays 24.

For example, the conveyor assembly 70 may comprise moving elements, forexample, conveyor belts 72, spaced apart from each other a distancesufficient to support the tray or trays 24 preferably without causingsubstantial interference with, for example, substantial shadowing of,effective light provided to the molds 2, for example as the molds 2 aremoved through the chamber 14. For example, the conveyor belts 72 may belocated so as to support opposing peripheral portions of the tray 24.The belts 72 transport the trays 24, loaded with filled molds 2, throughthe illuminated chamber 14 between the inlet portion 16 to the outletportion 18, preferably in a direction of travel that is substantiallyperpendicular to the longitudinal alignment of the lamps 54. In FIG. 3the belts 72 are structured to transport the mold filled trays 24 in adirection perpendicular to the plane of the page.

The conveyor assembly 70 may comprise, for example, a plurality ofconveyor elements, for example, conveyors belts 72 for accommodating oneor more trays 24. In a preferred embodiment, the conveyor assembly 70comprises a plurality of conveyor subassemblies, each subassembly beingeffective to carry or convey one or more trays 24 through the chamber14. For example, in the system 10 shown, the system 10 is sized andstructured to accommodate two “side-by-side” substantially parallelconveyor subassemblies 70 a and 70 b, wherein each of said conveyorsubassemblies comprises two motor driven, spaced-apart belts 72 locatedbetween the first light source 50 a and the second light source 50 b.

The conveyor assembly 70 is structured so that peripheral portions orperipheral edges of the tray or trays 24 rest upon and are conveyed byopposing belts 72 during the transport of the tray 24 through theilluminated chamber 14.

A problem with light emitting elements comprising ultravioletfluorescent tubes 54 is that the illumination intensity emitted by suchtubes tends to be inconsistent. Usually, illumination intensity tends todecrease from the center of the tube, where the illumination is mostintense, toward the end portions of the tube, where the illumination isless intense. Generally, each tube typically has at least one regionemitting a maximal level of radiation intensity and flanking regions oflesser intensity.

Thus, it can be appreciated that molds 2 disposed or transported inalignment with end portions of the tubes or lamps will generallyexperience lower light intensity than those molds 2 disposed ortransported in alignment with the central portion of the tube. Thus,molds in the tray 24 passing beneath the end portions of the fluorescenttubes may “see” a different intensity than more centrally located moldsin the same tray 24.

Inconsistencies between different molds cured in a single batch aregenerally undesirable. Structure is preferably provided, such as theoptical surfaces described elsewhere herein, to ensure that theeffectiveness of the cure process will not be dependent on where themold is positioned relative to its location on the tray 24. Preferably,the system 10 is structured such that each of the filled and closedmolds on the tray will experience substantially the same intensity ofultraviolet light as each other filled and closed mold. As discussedherein, such uniform or substantially uniform light exposure can providebenefits in terms of consistency and quality of the polymerized lenses.

It is an object of the invention to provide a system that providesuniform, consistent illumination to the plurality of molds 2 on the trayor trays 24, such that each and every filled mold “sees” or is exposedto the same intensity of light for the same duration of time, and thusevery mold assembly 2 is subjected to substantially identicalpolymerization or curing conditions.

In an important aspect of the invention, the system 10 includesstructure for effecting consistency, for example, uniformity ofillumination intensity provided to the molds 2.

For example, the system 10 may comprise one or more optical surfaceswithin the housing that are effective to reflect light from the lamps ina manner that will promote the desired substantially consistentillumination intensity. Such optical surfaces may be provided by one ormore reflective elements disposed within the housing. If a plurality ofreflective elements are provided, the elements may have one or moredifferent reflectivities, or may have the same reflectivities but arelocated in different positions with respect to the light sources.

For example, in some embodiments of the present invention, the system 10includes multiple reflecting surfaces positioned in the housing so as toprovide a more consistent, preferably more uniform exposure to the lightfrom the light sources to the tray, relative to an identical system withonly a single, uniform reflecting surface. For example, in someembodiments of the invention, optical surfaces disposed adjacent thetube end portions have a greater reflectivity relative to opticalsurfaces disposed adjacent the central portion of the tube. In anespecially advantageous embodiment of the present invention, one or morereflecting elements disposed above the tube end portions are selected tohave about 9.75% more reflectivity than the reflecting elements disposedabove the intermediary or central portion of the tube.

In the system 10 shown in FIGS. 2 and 3, the system 10 advantageouslycomprises structure, for example one or more optical surfaces 80, forenhancing consistency, preferably enhancing uniformity, of polymerizinglight intensity provided to the tray 24 and the molds 2 carried thereby.The optical surfaces 80 may comprise any suitable structure forachieving, or at least enhancing, effectiveness of the polymerization,for example, by enhancing consistency of the illumination provided tothe molds 2 as the molds 2 are moved through the housing 12.

The optical surfaces 80 may comprise reflective elements 80 a and 80 blocated within the housing 12, for example, above and below the firstand second light sources 50 a and 50 b respectively.

The reflective elements 80 a and 80 b may be made of reflectivematerials, for example, one or more metallic materials, for example,aluminium, for example aluminium sheets. As shown in FIG. 3, thereflective elements 80 a and 80 b are spaced apart from the lightsources 50 a and 50 b respectively. Advantageously, the reflectiveelements 80 a and 80 b are located at positions selected to achievesubstantially consistent intensity of light provided by the first andsecond light sources 50 a and 50 b to the molds 2, for example, in orderto provide substantially optimal cure conditions within the housing 12.

FIG. 4 is provided to illustrate a variation of this feature of theinvention. Specifically, FIG. 4 shows a system 10 a of the presentinvention which is similar to system 10. A primary distinction betweensystem 10 a and system 10 is that in system 10 a, optical surfaces 180are provided which comprise a first plurality of reflective surfaces 180a and a second plurality of reflective surfaces 180 b. The firstplurality of reflective surfaces 180 a comprises, for example,reflective elements 181, 182, 183 spaced apart from the first lightsource 150 a at variable distances. For example, peripherally locatedreflective elements 181 and 183 are located closer to the lamp 154 athan intermediately located reflective element 182. In this particularsystem 10 a shown, reflective elements 181 and 183, disposed adjacentend portions of the tube 154 a, are positioned closer to the tube 154than reflective surface 182, which are disposed adjacent a centralportion of the tube 154 a. The variation in spacing of the reflectivesurfaces 181, 182, 183 relative to the lamp 154 is preferably selectedto optimize uniformity of illumination intensity at the surfaces of themold assembly 2.

Similarly, a second plurality of reflective surfaces 180 b, comprisingreflective elements 184, 185, 186, are spaced apart at variabledistances from the second light source 150 b. More specifically, forexample, peripherally located reflective elements 184 and 186 aredisposed closer to lamps 154 b than intermediately located reflectiveelement 185.

In some embodiments, one or more of the optical surfaces comprises analuminum sheet having a selected reflectivity based on the grade of thealuminum. Aluminum sheets are commercially available, for example, fromsupplier Alanod Ltd, Chippenham Drive, Kingston, Milton Keynes MK10 OAN,United Kingdom which provides aluminum sheets in different grades. Suchsheets are typically identified by grades including grade 9040 GP, grade412 GS, grade 610 G3, grade 620 G grade 1100 G, and grade 4270 AG.

Other reflecting elements may also be utilized within the scope of thepresent invention. For example, a sheet made of a material selected fromPTFE, Polycarbonate, and Bright Annealed Steel can be utilized toprovide a desired reflectivity.

The following description provides examples of variations or ranges ofillumination intensity in the present systems when the systems includereflecting elements having different reflectivities, or differentrelative reflectivities.

FIG. 4A shows a diagram of illumination intensities at top surfaces of32 molds (numbered 1-32) aligned along an ultraviolet lamp tube 54 thatis set to deliver ultraviolet light at 500 μW/cm². In this embodiment, areflecting surface R1 made of a single grade of a reflective aluminumsheet is provided in a spaced apart relationship with the ultravioletlamp. The aluminum sheet has a grade of 610 G3. It may be understoodthat in this system, the system comprises an optical surface having asingle reflectivity. As shown, there is a variation in the illuminationintensity that is measured at the mold surfaces. This variation rangesfrom a minimum illumination intensity of about 450 μW/cm² adjacent theend portions of the tube 54 (molds numbered 1 and 32) to a maximum ofabout 500 μW/cm² adjacent the center portion of the tube 54 (moldsnumbered 8 through 25). Thus, it can be appreciated that the pluralityof filled molds are not being exposed to uniform, consistentillumination of ultraviolet light.

FIG. 4B shows a diagram of illumination intensities at surfaces of 32molds (numbered 1-32) aligned along an ultraviolet lamp tube 54 that isset at 500 μW/cm². In this embodiment of the invention, a reflectingsurface R2 is provided which comprises two different grades of aluminumsheet. More particularly, the reflecting surface R2 is made of analuminum sheet having grade 610 G3 adjacent a center portion of thetube, and aluminum sheets both having grade 4270AG adjacent end portionsof the tube 54. It may be understood that this system comprises anoptical surface with a plurality of different reflectivities or opticalproperties. As indicated, there is a variation in the illuminationintensity that is measured at the mold surfaces. This variation rangesfrom a minimum of about 480 μW/cm² adjacent the end portions of the tube(molds numbered 1 and 32) to a maximum of about 500 μW/cm² adjacent thecenter portion of the tube (molds numbered 4 through 29).

It can be appreciated upon comparison of FIG. 4A and FIG. 4B, thatalthough the plurality of filled molds are not being exposed to uniform,consistent illumination of ultraviolet light, the variation ofillumination intensity is significantly less in the embodiment of theinvention shown in FIG. 4B, than the variation of illumination intensityof the system shown in FIG. 4A. Moreover, a greater number of molds areexposed to the maximum illumination intensity (500 μW/cm²) relative tothe number of molds exposed to the maximum illumination intensity in thesystem shown in FIG. 4A.

FIG. 4C shows a diagram of illumination intensities at surfaces of 32molds (numbered 1-32) aligned along an ultraviolet lamp tube that is setat 500 μW/cm². In this embodiment of the invention, a reflecting surfaceR3 is provided which, like the set up in Example 4C, comprises twodifferent grades of aluminum sheet. However, reflecting surface R3comprises an aluminum sheet having grade 610 G3 adjacent a centerportion of the ultraviolet emitting tube 54, and aluminum sheets bothhaving grade 9040GP adjacent end portions of the tube. As indicated,there is a variation in the illumination intensity that is measured atthe mold surfaces. This variation ranges from a minimum of about 470μW/cm² adjacent the end portions of the tube 54 (molds numbered 1, 2, 31and 32) to a maximum of about 500 μW/cm² adjacent the center portion ofthe tube 54 (molds numbered 8 through 25).

It can be appreciated from FIGS. 4A, 4B, and 4C, that illuminationintensity is relatively more uniform at the mold surfaces in the systemshown in FIG. 4B. The range of intensity along the ultraviolet tube inFIG. 4A is from 450 μW/cm² to 500 μW/cm² whereas the range of intensityalong the ultraviolet tube in FIG. 4C is from 470 μW/cm² to 500 μW/cm².

Turning back to FIG. 3, in one embodiment of the invention, each of thereflective elements 80 a and 80 b comprises a first reflective surfaceR1 disposed adjacent end portions of the light emitting elements 54 anda second reflective surface R2 disposed adjacent a central portion ofthe light emitting elements, wherein the first reflective surface R1 hasa higher reflectivity than the second reflective surface R2.

In a preferred embodiment of the invention, two first reflectivesurfaces R1 are provided, each being disposed adjacent end portions ofthe fluorescent lamps, and each having a reflectivity that is about 6%to about 10% higher than a reflectivity of the second reflective surfaceR2 located adjacent a central portion of the fluorescent lamps, thefirst and second reflective surfaces being about equidistantly spacedfrom the lamps. More preferably, the first reflective surfaces R1 have areflectivity that is at least 6.75% higher than a reflectivity of thesecond reflective surface R2. Even more preferably the first reflectivesurfaces R1 have a reflectivity that is about 9.75% higher than areflectivity of the second reflective surface R2.

The following Table 7 shows direct comparisons of reflector materials.This Table is provided in order to identify differences in the differentmaterials useful as reflecting elements in the systems of the presentinvention. The maximum ultraviolet intensity seen at the mold tray wasmeasured for each of the different reflector materials. For eachmaterial the reflecting element was placed at two different distancesbehind or spaced apart from the ultraviolet tube.

There are generally two categories of surface finish, either matt orspecular. A matt surface finish gives a diffuse type of reflection. Aspecular surface finish gives a mirror-type of reflection. The term“optical surface” as used herein, refers to any surface used to controldistribution of light within the chamber of the system. This term isintended to encompass a range of surfaces, including but not limited tosurfaces having very low reflectivity values and surfaces having veryhigh reflectivity values.

In one aspect of the present invention, a diffuse surface for the mainreflector is preferred because a diffuse reflection generally breaks upthe directional component of the light, thereby providing more uniformillumination within the housing chamber.

In another aspect of the invention, one or more different lowreflectivity surfaces are provided, and are sometimes used inconjunction with more highly reflective surfaces.

Table 7 shows the maximum ultraviolet intensity recorded at the filledmold tray when a reflective surface is placed at a distance of either 0mm or about 40 mm above the ultraviolet lamps. The tray is positioned atabout 72.5 mm below the lower surface of the ultraviolet lamps. Theultraviolet lamps are 40 watt lamps that are set at maximum power. Theintensity is recorded at about the mid-point of the lamp.

TABLE 7 Reflector Distance from Lamp Surface Material 0 mm 40 mm FinishNone 1370 1370 — Bright annealed steel 1800 1830 mat * 1100 G 2070 2100mat * 610 G3 1980 2050 mat * 620 G 1980 2020 mat * 9040 GP 2160 2190patterned * 412 GS 2260 2300 specular * 4270 AG 2240 2250 specular PTFE1930 1950 mat Polycarbonate 1430 1420 mat * = aluminium sheet Maximumoven intensity Values in μW/cm2

An especially advantageous system 10B of the invention is shown, inpart, in FIG. 4D. Unless otherwise indicated herein, system 10B issubstantially the same as system 10. Generally, FIG. 4D illustrates afront cross sectional view of the system somewhat similar to the viewshown in FIG. 4. Like system 10 and 10A, system 10B includes upper andlower light sources 50 a and 50 b, each including a plurality of lightemitting tubes 54, and a conveyor assembly (not shown) for moving leftand right trays 24 containing molds (not shown) through the housing (notshown). The trays 24 are being moved in a direction generallyperpendicular to the page.

Optical surfaces are provided which are structured and positioned to beeffective to promote substantially uniform distribution of light ontothe trays, for example, onto top and bottom surfaces of the trays.

In this specific example, the optical surfaces comprise of upper opticalsurfaces 580 a and lower optical surfaces 580 b. Each of upper and loweroptical surfaces 580 a and 580 b, respectively, comprises a firstoptical surface RR1 having a first reflectivity, and at least one secondoptical surface RR2 having a second reflectivity that is greater thanthe first reflectivity.

Optionally, the first optical surfaces 580 a and/or the second opticalsurfaces 580 b may further include a third optical surface RR3, having athird reflectivity. In this specific example, third reflectivity isgreater than the second reflectivity.

For example, the first optical surface RR1 is preferably between about0% and about 30% reflective. For example, the first optical surface RR1may have 0% reflectivity. More specifically, the first optical surfaceRR1 may comprise, for example, a Matt Black painted surface or a blackanodized surface.

The second optical surface RR2 is preferably between about 10% and about50% reflective, or greater. For example, the second optical surface RR2may have about 30% reflectivity. More specifically, the second opticalsurface RR2, may comprise, for example, a Matt Gray painted surface or agray anodized surface.

In certain embodiments, the present systems and methods use ANOLOK blackanodized surfaces and ANOLOK gray anodized surfaces (ANOLOK is atrademark of Alcan Aluminium UK Limited). The use of anodized surfacescan help reduce or eliminate fading of the color resulting from UVexposure that may negatively affect the curing properties of the lensmaterials.

Both first and second optical surfaces RR1 and RR2 may comprisesubstantially planar surfaces, disposed, for example, in a planesubstantially parallel to and substantially uniformly spaced apart fromthe light sources 50 a and 50 b, respectively. Optical surfaces RR1 andRR2 may comprise any suitable material and structure, for example,optical surfaces RR1 and RR2 may comprise a layer of paint, film,coating, or the like, for example, located on or adjacent to top andbottom inner walls of the housing. The optical surfaces may thus be alayer or coating disposed on a rigid substrate, such as a metal sheet.

The third optical surface RR3, if provided, is preferably a metallicsurface having a relatively high reflectivity compared to second opticalsurface RR2. For example, third optical surface RR3 may comprise anAlanod Micro Silver 4270 reflective surface.

The third optical surfaces RR3 are disposed so as to face generallyinwardly into the housing chamber and toward the moving trays, forexample, in a direction substantially perpendicular to the lamps. Asshown in FIG. 4E, optical surfaces RR3 may include slotted regions sizedshaped to receive a circumferential region of the lamps 54. The slottedstructure facilitates lamp replacement.

FIG. 4D′ shows a plan view of the optical surfaces along line 4D′-4D′ inFIG. 4D. It can be seen that in this embodiment, the optical surfacesRR1, RR2, and RR3 are provided in a plurality of strips that areparallel to the direction of movement of the trays carrying the molds.Surface RR1 is matt black, and surfaces RR2 and RR3 are matt grey, asdiscussed herein. In one embodiment, in which the ultraviolet lamps areabout 3 feet long, the RR3 regions have a width of about 10 inches, andthe RR2 region has a width of about 16 inches. However, these values areprovided by way of illustration and should not be construed to limit theinvention.

The optical surfaces used in the present systems are preferablypositioned and structured to achieve at least one of, and preferably allof, the following objectives: provide a means, for example a mechanism,for compensating for the natural loss in lamp intensity near the lampsends; reduce the occurrence of light from the lower lamps from beingreflected by the surfaces behind the upper lamps; reduce the occurrenceof light from the upper lamps from being reflected by the surfacesbehind the lower lamps; and provide a substantially even light intensitydistribution over the surfaces of the trays regardless of the number oftrays are on the conveyor and/or the positioning of the trays on theconveyor. Thus, it can be understood that the present systems includeone or more elements or features that are effective in providing adesired or predetermined amount of controlled illumination of the moldassemblies 2.

Thus, the system 10 b can be understood to include a conveyor for movinga plurality of trays through a housing for polymerization of lensprecursor materials disposed in molds arranged on the trays. The lightassembly includes ultraviolet lamps disposed both above and below thetrays carrying the molds.

This arrangement gives rise to certain considerations regarding theoptics in the system, particularly when the system is configured to beused for polymerizing lenses using especially low intensities ofultraviolet light, for example, as described elsewhere herein. In suchsystems in accordance with the invention, tight control of the lightprovided to the molds during the manufacturing process will promoteconsistency in quality of the lenses produced.

Gaps between adjacent trays moving along the conveyor (such as shown,for example, in FIG. 6) may cause or be associated with inconsistentillumination provided to edge portions of the trays. For example, it canbe determined that when highly reflective aluminum surfaces are usedbehind the lamps to reflect light from the lamps as described elsewhereherein, the gaps can cause leading and trailing edges of the uppersurface of each of the trays to be exposed to reflections from the lampsbeneath the trays. In a similar manner, leading and trailing edges ofthe lower surface of each of the trays are exposed to reflections fromthe lamps above the trays.

In order to reduce or minimize these undesirable reflection effects, theoptics of the system are modeled using a light ray tracing softwarepackage manufactured and sold under the name Photopia. A ray tracinganalysis is performed and results of the analysis indicate that theeffects described above could be minimized, or at least reduced, forexample, substantially reduced, by using optical surfaces havingrelatively low reflectivity.

It is still deemed desirable that compensation is made for the loss inlamp intensity near the lamp ends in the system. As mentioned elsewhereherein, a characteristic of a typical fluorescent tube is that lightintensity emitted near end regions of the tube is relatively lower thanlight intensity emitted in a more central region of the tube.Consequently, filled closed molds under the end regions of the tubewould experience lower light intensity than those under the centralregion of the tube. In order to compensate for this variation along thelength of the tube, it is determined that uniformity of light could bepromoted by adding optical surfaces adjacent, for example behind, thetube ends having a relatively higher degree of reflectivity.

Computer simulations using the ray tracing software package Photopiashow that a combination of a Matt Black surface with about 0%reflectivity and a Matt Grey surface with about 30% reflectivityarranged as shown in FIG. 4D and FIG. 4D′, with the lamps being poweredat about 60% output, can meet the above objectives. The arrangement mayalso include side reflectors arranged as shown in FIG. 4E in order tofurther improve the optics in the system.

After the changes are made to the system using the appropriate opticalsurfaces in appropriate locations, the ray tracing analysis can again beperformed, to determine if substantially consistent illuminationintensity is provided to each of the trays or molds located on the traysmoving through the housing regardless of the number of trays or thepositioning of the trays.

In accordance with another aspect of the present invention, the system10 is structured to provide that each of the filled molds aresubstantially instantly, or substantially instantaneously, illuminatedwith effective light having the correct intensity when polymerization isinitiated. Likewise, the system is structured such that each of themolds is substantially instantly, or substantially instantaneously,removed from exposure to effective light when polymerization iscomplete, or substantially complete. In other words, the system isdesigned such as to provide means, for example mechanisms, for effectingsubstantially instantaneous commencement and substantially instantaneoustermination of effective light, for example, optimally effective light.

In certain embodiments, the nearly instantaneous exposure of the moldassemblies to the radiation or ultraviolet light can be provided by oneor more of the following: light shields, such as fixed panels, moveablegates, and the like, and tray moving devices, such as draggingmechanisms that provide a faster rate of movement relative to theconveyor system of certain of the present systems.

For example, another advantageous feature of the system 10 is shown insimplified cross-sectional view in FIG. 5. As illustrated, housing 12 isstructured such that inlet 16 provides a substantially shaded region 189within the housing 12. More specifically, the substantially shadedregion 189 is a region within the housing 12 that is shielded fromexperiencing regions of illumination intensity less than a desiredillumination intensity.

For example, in a preferred embodiment of the invention, the inletportion of the housing is structured to shield the tray from receivingeffective light (i.e. light having an illumination intensity effectiveto cause, initiate or otherwise effect polymerization of the compositioncontained in the molds) when the tray is located in the inlet portion.The inlet portion may comprise an enclosable vestibule sized to containat least one tray. The interior of the vestibule is shielded from lightfrom the interior of the illuminated portion of the housing by means ofa barrier, for example, a moveable gate, such as a pneumaticallycontrolled gate, that can be opened, for example automatically opened,to facilitate movement of the mold filled tray onto the conveyor andinto the illuminated portion of the housing.

Preferably, the outlet portion of the housing comprises a similarenclosable vestibule for preventing overexposure of the mold assembliesto effective light after the composition has been cured.

Another feature of the invention for preventing premature exposureand/or overexposure of molds to effective light comprises an inletshielded region located inward from the inlet vestibule and an outletshielded region located inward from the outlet vestibule.

For example, housing 12 may be structured to provide a region 189 ateach of the inlet 16 and outlet (not shown in FIG. 5) within the housing12 which is shielded from effective light. In other words, region 189receives substantially no light that is effective to cause or initiatepolymerization of the polymerizable composition contained in the moldswhen the molds are located in region 189.

More specifically, housing 12 may include a “letter-box” type inlet 16and/or outlet, comprising preferably inwardly extending structure 190,disposed between peripheral regions of the light source 50 emittingelements 54′ and the molds 2 on or in the tray 34 when the tray 34 islocated within the shielded region 189.

More specifically, shield structure 190 may include upper shield portion190 a and lower shield portion 190 b each of which extends inwardly intothe housing 12. The shield portions 190 a and 190 b are spaced apart bya distance sufficient to allow passage of a mold filled tray between theshield portions 190 a and 190 b.

Preferably, at least one light emitting tube 54′, for example, two lightemitting tubes 54′, are located immediately above shield portion 190 aand, similarly, at least one light emitting tube 54′, for example, twolight emitting tubes 54′, are located below inwardly extending shieldportion 190 b.

The advantages of the shield structure 190 might be better understood asfollows. The illumination intensity adjacent each lamp 54, for exampleunder each lamp 54 of the first light source 50 a for example, isreinforced by the two lamps that are directly adjacent or flanking eachside of the lamp. As a result, the illumination intensity under theperipherally located lamps, or end lamps, for example lamps 54′, is lessthan the illumination intensity under the more centrally located lamps,in that the peripheral lamps 54′ do not have two directly adjacentflanking lamps on one side thereof.

As a result, without the shield structure 190, system 10 would include afully illuminated portion of the housing chamber 14 between thecentrally located lamps flanked by peripheral regions or end regions ofrelatively lower illumination intensity. Because the molds must passinto the opening 16 there is a risk that the molds would be exposed tothis region of lower illumination intensity. As a result of beingexposed, even briefly exposed, to this lesser region of illuminationintensity, the molds may not polymerize correctly. The shield structure190 provides one effective means of reducing the potential that one ormore of the molds would be exposed to illumination intensity that isdifferent from, for example, is less than, than the most effective oroptimal illumination intensity. Shield structure 190 is provided toeffectively “shade” the molds from receiving any significant prematureexposure to the lower intensity light, particularly, for example, whenthe molds are in the process of passing into, or out from, the fullyilluminated portion of the chamber 14.

For example, turning now to FIGS. 2 and 6, the system 10 shown, includesabout forty ultraviolet lamps 54 or tubes arranged above the conveyorassembly 70 and about forty ultraviolet lamps 54 arranged below theconveyor assembly 70.

FIGS. 7A and 7B illustrate the effectiveness of the shield structure 190feature of embodiments of the present systems. FIG. 7A shows a diagramof illumination intensities without the shielding feature. At the inletto the system, the molds approach lamp 1 (L1) along conveyor (in thiscase, moving from right to left). The scale shows, in units of μW/cm²,the ultraviolet intensity level measured at certain points along theconveyor provided by the first three lamps in a 40 lamp arrangement. Thetarget illumination intensity is 900 μW/cm². The scale shows that theillumination intensity under the 1st and 2nd lamps (L1 and L2) and alongthe approach to L1, (0 to 180 mm) the illumination level issignificantly below the target illumination intensity level of 900μW/cm².

Turning now to FIG. 7B, the letter-box design, or shield structure, ofthe inlet portion 16 shields each filled closed mold assembly 2 from thelower intensity ultraviolet light (illumination intensities of less than900 μW/cm², for instance) until the mold assembly 2 reaches the 3rdlamp. Advantageously, the letter-box design still allows light from the1st and 2nd lamps to reinforce light from the 3rd lamp. Therefore, itcan be appreciated that when under the 3rd lamp, each filled closed moldis exposed to ultraviolet light with the correct intensity in asubstantially instantaneous manner.

It is to be appreciated that the inwardly extending structure 190 thatmakes up the letter-box inlet may sometimes extend not as far as, orfurther into the housing chamber than shown and specifically describedherein, so long as the areas of lower ultraviolet intensity are shieldedfrom reaching the molds by such inwardly extending structure. Such otherarrangements are considered to be within the scope of the presentinvention.

In yet another aspect of the present invention, the system 10 preferablyis structured such that the edge belt conveyor assembly components, forexample, the belt supports, do not substantially shield the filled molds2 on the edges of the tray from receiving the correct or desired orpredetermined light intensity. In the embodiment of the invention shownin FIG. 3, the edge belt conveyor assembly 70 is constructed usingoutriggers and supports that are structured to position the tray 24 awayfrom the peripheral support components of the system 10 in order toprovide reduced illumination shielding.

Reduced illumination shielding within the chamber 14 can be accomplishedby any suitable structural means, one of which is shown in FIG. 3 and indiagrammatical form in FIG. 8. The edge belt conveyor assembly 70includes first and second outriggers 92, 94 connected to support posts96. Support post 96 is one of a plurality of spaced apart posts thatholds support beam 95 that runs the length of the system. The supportbeam 95 supports the first outrigger 92 which hold the conveyor belt 72.The support beam 95 is mounted to the spaced apart support posts 96 bysecond outrigger 94 which extends away from the side wall of thehousing.

The advantages of this structure may be more greatly appreciated byreferring to FIG. 8. In diagrammatical form, it can be seen that thefirst and second outriggers 92, 94 are substantially perpendicular tothe supports 95, 96 and effectively position the molds in a region offull illumination. This assembly is effective to prevent any substantialillumination shielding or shadowing from occurring on the molds due tothe presence of the various components of the conveyor assembly 70. Thisstructure eliminates, or at least reduces, any shielding of the filledmolds from the polymerizing light and allows each tray 24.

The same principles of optimal illumination and reduced illuminationshielding could be applied to the construction of other parts orcomponents of the system 10 in accordance with the present invention.

Referring now specifically to FIG. 3, a central conveyor support 98 isprovided so that sized and shaped to reduce the occurrence of shieldingof the filled molds by within the interior of the system 10. In thisembodiment, the central support 98 includes spaced apart main supportposts 98 a having outriggers 98 b (only one support post 98 a andoutrigger 98 b is shown in this view). These posts 98 a are situated atregular intervals and supporting the structure above them. The structureabove them includes a support beam 98 c that runs the length of thesystem 10.

Along the length of the central conveyor support 98 there are both lefthanded support posts 98 a and right handed support posts. They alternateleft handed, right handed, left handed, right handed, etc. A cantilever98 d is mounted on top of the intermediate support beam 98 c as shown.The cantilever 98 d includes a right hand arm and a left hand arm, eachof which supports a conveyor belt 72 as shown.

In order to provide an effective cure of the lens precursor monomercomposition in the molds, it is preferable that the commencement andtermination of illumination of the molds is substantially instantaneous.Instantaneous and consistent illumination is particularly important atthe commencement or the beginning of the cure because it is believedthat many of the important lens properties are determined in the firstfew minutes of the curing cycle. As mentioned elsewhere herein, it isalso preferable that system be designed so as to maintain a consistencyof illumination intensity throughout the cure period.

Another important consideration given to the design of the system 10 ofthe present invention is the benefits of achieving instantaneousillumination, the benefits of which are described elsewhere herein, foreach mold when the mold is first placed on the conveyor assembly 70. Insome embodiments of the invention, the conveyor assembly travels at aspeed of about 2 meters per hour to about 5 meters per hour, for exampleat about 3 meters per hour.

In embodiments of the invention in which the conveyor assembly 70 movesthe tray 24 through the housing 12 at only approximately 3 meters perhour, this means that it will take an individual filled contact lensmold, with a diameter of about 20 mm, about 24 seconds to move throughthe entrance to the fully illuminated region of the chamber 14.Similarly, it will take about the same length of time for the mold toleave the fully illuminated region of the chamber 14. The filled moldwould therefore not be exposed to the desired instantaneousillumination, in that the leading edge of the mold would be exposed toeffective light before the trailing edge of the mold.

Preferably, the system 10 includes a mechanism or device for reducingthe time a lens mold takes to be moved into the region of effectivelight. For example, the system may further comprise a “fast drag”mechanism or device effective to provide molds with substantiallyinstantaneous illumination of the desired or optimal intensity at thestart of the cure, and a substantially instantaneous termination of thelight exposure at an end to the cure.

FIG. 6 illustrates this aspect of the present systems. In order toachieve the desired “instantaneous illumination” of molds, the system 10preferably further comprises a mechanism for controlling speed of thetray through the inlet and outlet portions of the housing chamber 14 inorder to achieve the desired illumination intensity provided to themolds during the cure period.

For example system 10 may include a mechanism 200 for rapidly moving thetray 24 containing the molds, from the inlet portion 16, whichpreferably includes the shield structure 190, into the fully illuminatedchamber. Mechanism 200 may sometimes hereinafter be referred to as the“fast-drag” mechanism.

For example, as illustrated in FIG. 6, a mold filled tray is shown atseparate times as the tray moves through the system 10. The mold filledtray is represented by numerals 24 a, 24 b, 24 c, 24 d and 24 e, whichrepresent the mold filled tray at different points in time. Thefast-drag mechanism 200 may comprise a drag arm 202 structured to grasp,clamp or otherwise temporarily engage the tray 24 a while the tray 24 ais located within the inlet 16 (tray 24 a is shown being grasped by dragarm 202 in dashed line in FIG. 6). The mechanism 200 may furthercomprise a drag arm guide 204 structured to rapidly move the drag arm202, and tray 24 a engaged thereto, through the inlet portion 16 of thehousing 12 and into the fully illuminated portion of the housing chamber(for example, the portion of the chamber illuminated by the 3^(rd)through 38^(th) lamps). Generally, the fast drag mechanism 200 isdesigned to very rapidly pull or rapidly drag a mold filled tray 24 afrom the letter-box style inlet portion 16 or a vestibule adjacent aninlet of the housing having substantially no ultraviolet radiation, intothe centrally located portion of the housing chamber that is fullyilluminated with the desired consistent illumination intensity.

The drag arm 202 is structured to be capable of releasing the tray 24 aonto the conveyor belt (not shown in FIG. 6) at the moment the tray 24 bis positioned substantially entirely within the fully illuminatedportion of the housing chamber. At that point, the tray 24 b, nowreleased from the drag arm 202, is moved or conveyed through the fullyilluminated portion of the housing chamber by means of the moving edgebelt (not shown), which allows each mold on the tray 24 b to be exposedto the full illumination of ultraviolet light for the complete cureperiod. The tray within the fully illuminated portion of the chamber isindicated as tray 24 b, 24 c and 24 d in FIG. 6. At the end of the cureperiod, another fast drag mechanism 200 near the outlet 18 is used in asimilar fashion to rapidly pull the tray (to position of tray 24 e) outof the fully illuminated portion of the chamber 14 and instantaneouslyend the exposure to the effective light.

In a specific embodiment of the invention in which the system isdesigned for the manufacture of silicone hydrogel contact lenses, theconveyor assembly 70 provides for continuous, steady conveyance of thetray 24 c though the fully illuminated chamber, for example, at a steadyrate of about 3 meters per hour in order to provide a cure period havinga duration of at least about 40 minutes to about 1 hour.

It is noted that in various experiments performed during development ofthe present systems, lenses were made after only about 20 minutes orabout 30 minutes in the illuminated chamber 14. However, some of theselenses were found to have undesirably high levels of extractables orunreacted monomers, indicating that they were not fully polymerized. Ina preferred embodiment, one hour is a preferred cure duration, with 40minutes being the preferred minimum cure duration.

Other alternative or additional mechanisms may be provided by the system10 of the present invention which address the importance of aninstantaneous beginning and an instantaneous end to the cure of thecomposition within the molds. The fast drag mechanism 200 provides aneffective means for example mechanism for accomplishing this objectivein that the monomer filled molds are quickly moved from an area ofsubstantially no polymerizing radiation (for example, in the shieldedinlet portion or in the vestibule) into the fully illuminated chamber.At the end of the cure, for example, a cure having a duration of betweenabout 30 minutes to about a one hour, the molds are rapidly removed fromthe fully illuminated chamber by means of the fast drag arm.

By providing a fast drag mechanism or device in the present systems, ithas been discovered that certain shield components may not be required.For example, portions of the “letter box” inlet may not be required.Thus, in certain embodiments of the present systems, the upper panel ofthe letter box inlet, such as panel 190 a illustrated in FIG. 7B, can beomitted and still achieve the desired polymerization of the lensprecursor material.

In view of the disclosure herein, one specific embodiment of the presentsystems can be understood to comprise a housing and a plurality ofultraviolet lamps located in the housing. The housing comprises an inletand an outlet. A vestibule is provided at each of the inlet and outletof the housing. The housing also comprises a plurality of conveyor beltsto move a tray of filled mold assemblies pass the ultraviolet lamps topolymerize a lens precursor composition located in the mold assemblies.The housing includes a moveable, light shielding gate between the inletvestibule and the housing inlet, and a moveable, light shielding gatebetween the housing outlet and the outlet vestibule. The housing alsoincludes a fast drag mechanism, as described herein. At the inlet andoutlet of the housing, a lower panel is provided extending over thefirst two ultraviolet lamps in the housing, and a different lower panelis provided extending over the last two ultraviolet lamps in thehousing. In this embodiment, an upper panel, such as panel 190 a in FIG.7B, is not present. The housing also comprises optical surfaces thatinclude a central region having 0% reflectivity (e.g., a matt blacksurface), and peripheral regions having 30% reflectivity (e.g., a mattgrey surface). Thus, this system provides the desired light shieldingprior to the curing process of the lens precursor composition, providesa rapid entry and exit of trays carrying filled mold assemblies, andprovides substantially uniform illumination of the mold assemblies andthe lens precursor composition contained therein to produce contact lensproducts of acceptable quality.

Turning now to FIG. 8A, another advantageous feature of the presentinvention is shown which is useful for monitoring system 10 for qualitycontrol purposes, for example. More particularly, the systems 10 of thepresent invention may comprise means for measuring and/or monitoringlight intensity, for purposes of validating and/or mapping lightintensity at various locations or positions within the chamber 14.

For example, at least one, preferably a plurality of, sensor devices300, suitable for being moved through the system housing are provided.The sensor device or devices 300 may comprise a remote data logger 302having a sensor window 304 for sensing and recording, for examplelogging, intensity of light provided to the sensor device 300 throughthe sensor window 304.

For example, each sensor device 300 may comprise an integratingradiometer, or other technology known to those of skill in the art,suitable for sensing, recording and logging light intensity values.

Advantageously, the sensor devices 300 are sized and structured to bepositionable within the housing chamber and moved therethrough. Moreparticularly, the data loggers 302 are structured so that they can bemoved through the system during processing of lenses.

For example, as shown in FIG. 8A, three data loggers 302 are shownpositioned on tray 24, which is identical to the trays used to hold andmove the filled molds through the illuminated chamber. In thearrangement shown, one sensor 304 is being used to monitor one of eachof the edge positions and one sensor 304 is being used to monitor anintermediate position on the tray 24.

The data loggers 302 are sized and structured so as to enable three ofsuch data loggers 302 to be placed on a single tray 24, such as shown inFIG. 8A. For example, each data logger 302 has a thickness of about 20mm, a length of 160 mm, and a width of about 100 mm.

Turning now to FIG. 8B, a diagram is shown of an eighty (80) lamp system10 in accordance with the invention described and shown elsewhere herein(for example, in FIG. 6). This diagrammatical view illustrates aneffective means of monitoring a plurality of positions in theilluminated chamber using the sensor devices 300 positioned on traytrays 24 for example as shown in FIG. 8A. In FIG. 8B, each “track” ofwhich a filled contact lens mold moves through the system can be tracedby a sensor window 304 of a data logger 302 appropriately placed. Eachtrack represents a position of a mold passing through the illuminatedchamber.

The use of the sensor devices can be described as follows. A system,such as system 10 described and shown elsewhere herein, is provided formanufacturing contact lenses using ultraviolet light. A single contactlens mold takes one hour to pass through the housing of the system.

Six sensor devices, or data loggers 302, are arranged as shown in FIG.8A on two mold trays, three data loggers to each tray. Contact lensmolds (not shown) may also be placed on the trays along with the sensordevices if desired. Alternatively, the data loggers can be provided ontheir own tray free of contact lens mold assemblies, and the data loggercontaining trays can pass through the system while trays containingfilled contact lens mold assemblies are also passing through the system.For example, during the lens manufacturing process, two of the traysthat normally would carry contact lens molds through the housingchamber, are replaced with the two trays each holding the three dataloggers. The two trays holding the data loggers are passed into thehousing chamber, along with trays holding lens molds, and are movedthrough the housing chamber by means of the conveyor.

During the one hour time period that a single data logger takes to movethrough the system, the sensor window of the data logger senses andrecords 65,536 values of light intensity. After the data logger leavesthe chamber, it is then connected to a computer. The 65,536 values aredownloaded into a software package and displayed on a computer screen,for example, in graph form. A technician can analyze the data andconfirms that the ultraviolet light intensity inside the housing is (oris not) at the desired level through a full cure cycle at a given moldposition.

In some embodiments of the invention, using the data loggers ispreferable to using fiber optic sensors and spectrometers as describedelsewhere herein for monitoring light in the system. For example, theremote data loggers are generally less expensive than fiber opticsensors. It should be appreciated that a combination of fiber opticsensors/spectrometers and data loggers may be provided in a system inaccordance with the present invention.

It is contemplated that the effectiveness of the sensor devices (e.g.data loggers) as described herein, may be enhanced by provision of anyone or more of the following: wireless real time communication upgrades,networking nodes, and enhancements to data processing capability. Thesesensor devices can be used as a part of an intelligent network. Otheradvantageous additions, modifications and alternative arrangements maybe provided for enhancing control and monitoring capabilities inaccordance with other embodiments of the invention.

In another aspect of the invention, means are provided for detectingfailure of individual light sources. For example, in the specificembodiment of the invention shown in FIG. 6 and described in detailelsewhere herein, it is important for an operator of the system 10 beaware and to know with some degree of certainty, that all of the 80lamps of the system 10 are properly functioning during the curing of thelenses. If any one of the lamps are non-functioning, it is possible orlikely that the contact lenses manufactured within the system 10 may notexperience the most effective cure. It is therefore desirable for thesystem 10 to include an effective and reliable control system that canreadily identify if one or more individual lamps has failed to operate.

Preferably, control of the lamps in the system of the invention isprovided by a control assembly comprising an electronically controlledlamp failure detection mechanism. Preferably, the control assemblyincludes components which can be implemented into the system atrelatively low cost and complexity. A lamp error feedback solutioncontrol assembly is preferred over more expensive, more complex and/orless reliable control means, for example, mechanisms that would utilizeradiometric sensors or fiber optic sensors.

More specifically, for example, lamp error feedback can be implementedinto the system of the present invention by connecting a pair offluorescent ultra violet lamps to a digital high frequency electronicballast and making use of digital addressable lighting interfaceprotocol (in the lighting industry this is commonly referred to as DALIprotocol). It is believed that DALI protocol has not previously beenimplemented in any system utilizing ultraviolet light to effectpolymerization of monomers. However, DALI protocol-based technology iswell known, and thus will not be described in great detail herein. Forexample, DALI protocol-based technology is conventionally implemented inlighting systems that control visible lamps in modern buildings.

The implementation of DALI protocol-based technology into the systems ofthe present invention is utilized in conjunction with digital highfrequency electronic ballasts. The DALI protocol will not communicatewith analogue ballasts. Means for controlling the ultraviolet lightsources in the systems of the present invention therefore, preferablyincludes digital ballasts, for example, digital, high frequencyelectronic ballasts connected to the lamps rather than analog ballasts.Modern digital electronic ballasts perform the basic function ofballasting a fluorescent lamp significantly better than analog ballastsin terms of power factor, efficiency, and the like.

For example, the digital ballast gives off less heat compared to anequivalent analog ballast.

For example, the electronic ballast may include a rectifier for changingthe alternating current (AC) from a power line into direct current (DC)and an inverter for changing the direct current into alternating currentat high frequency, typically 25-60 kHz. Some electronic ballasts includea boost circuit located between the rectifier and the inverter.

Generally, methods of lighting control in accordance with someembodiments of the present invention involve using digital controlsignals, preferably DALI protocol based technology, to control theelectronic ballasts, controllers and/or sensors belonging to the systemof the invention. In some embodiments of the invention, each componentof the lamp control and lamp failure detection system has its owndevice-specific address, and this makes it possible to implementindividual device control.

For example, as shown in a simplified diagram in FIG. 9, in accordancewith a preferred embodiment of the invention, a control assembly 400 isprovided which utilizes a digital ballast 422 connected to a pair oflamps 54. The digital ballast 422 is connected to an electroniccontroller 430. The control assembly is designed such that if one of theultraviolet lamps 54 turns off, for example, due to lamp failure or apoor electrical connection, the digital ballast 422 will send an errormessage to the electronic controller 430 using the DALI protocol. Theelectronic controller 430 receives the signal and causes an alarm (notshown) to sound, and provides indication as to which of the lamps hasfailed. An operator can then take corrective action. For example, theaction to be taken may include rejecting the contact lenses that passedthrough the system 10 at the time of the lamp failure. The operator canthen change the faulty lamp or fix the faulty connection.

In a specific embodiment of the invention, each of the ultraviolet lamps54 comprises a Philips TL40W/05 ultraviolet fluorescent lamp, or a lamphaving properties similar thereto. Each of the lamps 54 is connected toa Tridonic PCA 2/36 EXCEL 220-240V 50/60/0 Hz digital high frequencyballast 422.

The electronic controller 430 may include DALI protocol-based softwareembedded in a Beckhoff BC9000 programmable logic controller. The DALIprotocol-based technology, useful in the systems and methods of thepresent invention, is available from Hayes Control Systems Ltd, TheBoathouse, Henley-on-Thames, Oxon RG9 1AZ, United Kingdom, and MarlinAutomated Manufacturing Systems, Marlin House, Johnson Road, FernsidePark, Wimborne, Dorset BH21 7SE, United Kingdom.

It is noted that in addition to the identification of individual lampfailure, the control assembly 400 described hereinabove is preferablyalso configured to control lamp intensity. This may be accomplished byadding ultraviolet sensors, for example about ten ultraviolet sensors tothe 80 lamp system described in detail herein. The sensors may be UVAtype sensors. The supply voltage may be 24 volts, with the outputvoltage being about 0 to 10 volts. The output from the sensors may beused to control the lamp intensity through the hardware componentsdescribed herein with reference to the DALI protocol. The sensors may beprovided adjacent one or more of the ultraviolet lamps. In certainembodiments, the sensors are sensing the ultraviolet light duringexposure of the filled mold assemblies to the ultraviolet light. Forexample, the monitoring and measuring of UV intensity is occurringsimultaneously with the mold exposure to the UV light. In otherembodiments, the sensors do not sense or monitor the ultraviolet lightwhile the filled mold assemblies are exposed to the light. Instead, thesensors can monitor the light when the housing is free of moldassemblies undergoing the curing process.

FIG. 10 shows yet another system in accordance with the invention,generally at 510. Except as expressly described herein, system 510 issimilar to system 10 and features of system 510 which correspond tofeatures of system 10 are designated by the corresponding referencenumerals increased by 500.

System 510 is substantially the same as apparatus 10, with the primarydifference being that system 510 includes no conveyor system fortransporting the molds 2 through the housing 512 during the cure period.In other words, rather than the molds 2 moving through the housing 512during the polymerization process or cure period, the molds in system510 remain relatively substantially stationary, or relativelysubstantially static, during the polymerization process or cure period.For this reason, system 510 is sometimes referred to herein as a “staticlight box” system.

System 510 comprises a housing 512 having an opening 516 for receiving atray 524 filled with molds 2, a first light source 550 a comprising, forexample, six ultraviolet lamps 554 a and a second light source 550 bcomprising, for example, six ultraviolet lamps 554 b. The system 510further comprises structure, for example, tray guides, for example,slotted tray guides 236, positioned along inner sidewalls of the housing512 and structured to support the tray 524 and molds carried therein, ina position between the first light source 550 a and the second lightsource 550 b.

The system 510 is structured such that during the cure period, each ofthe molding assemblies 2 held by the tray 524 is positionedsubstantially directly between the centrally located light emittingelements 554 a and 554 b. Each of the filled molds 2 on the tray 524 ispreferably positioned substantially directly in the center of thehousing 512. For example, in the twelve lamp arrangement shown, each ofthe molds 2 are positioned beneath and above the 3rd and 4th lamps inthe first and second light sources 550 a and 550 b, respectively.

The molds 2 are preferably grouped together near a middle region of thetray 524 where the light intensity is substantially uniform. Forexample, in the static light box system 510 shown, the peripheralregions 524 a of the tray 524 hold no molds.

Use of the system 510 for manufacturing ophthalmic lenses from apolymerizable composition may include the steps of illuminating thehousing chamber 512 by activating the lamps 554 a and 554 b, and placinga mold-filled tray 524 into an opening 516 so that the tray 524 isengaged within the tray guides 236.

Preferably, because of the highly sensitive nature of some of thepolymerizable compositions used in the systems of the invention, thestep of placing the mold-filled tray 524 into the housing 512 isaccomplished very quickly, preferably as close to instantaneously aspossible, in order to achieve substantially instantaneous illuminationof each of the molds 2. For example, the tray 524 can be moved veryquickly into position by sliding it along the tray guides 236. The tray524 may be left to remain substantially static in the housing chamber514, between the first light source 550 a and the second light source550 b for the duration of the cure. To end the cure, the tray 524 israpidly drawn out of the housing 512 through the opening 516.

Although not specifically shown, it should be appreciated that ratherthan having a single opening 516 that functions as both an inlet andoutlet, the system 510 may, in other embodiments of the invention,comprise a distinct inlet opening for receiving the tray 524 into thehousing 512 and a distinct outlet opening for passing the tray 524 outof the housing 512.

In a preferred embodiment, the tray 524 is simply manually placed, forexample, slid, into the housing 512 through the opening 516 and when thepolymerization of the lenses is complete, the tray is manually retrievedfrom the housing 512 though the opening 516.

In some embodiments, an engagement mechanism 255 is provided. Theengagement mechanism 255 is structured to be effective to contact orengage, and move, for example, oscillate, the tray 524 during the cureperiod. Engagement mechanism 255 may include a grip mechanism 256structured to be releasably coupled to tray 524. The engagementmechanism 255 may include an arm 257, for example coupled to the gripmechanism 256. The arm 257 may be coupled to a damped pneumatic cylinder258. The engagement mechanism 255 may be driven by a motor (not shown)to move, for example, oscillate, the tray 524 in a desired fashion toachieve the most effective cure.

When low intensities of light are used to cure the polymerizablecompositions, as will be appreciated from the description of otherembodiments of the invention elsewhere herein, the step of placing thetray 524 into the housing 512 is preferably accomplished very quickly,preferably as close to instantaneously as possible. The system 510 isstructured to facilitate moving the tray 524 into and/or out of thesystem 510 as quickly as possible. In a specific embodiment of theinvention, system 510 is structured to be effective to enable processingin the system 510 of about 64 lenses per hour.

In some embodiments, one or more mechanisms may be provided forautomatically drawing tray 524 into the chamber 514 and/or out from thechamber 514. For example, engagement mechanism 255 may be useful to drawthe tray 524 into the chamber and/or push the tray out of the chamber514, and/or to gently move, for example, oscillate the tray back andforth within the chamber 514 during the cure period, if oscillation isdeemed to be beneficial. In other embodiments of the invention, separatemechanisms may be employed for drawing the tray 124 into and/or out ofthe illuminated chamber and for oscillating the tray 124.

During the cure period, the molds 2 are all positioned generally betweenthe centrally located lamps and in the fully illuminated region of thehousing chamber 514. The polymerizable composition in the molds 2 isthen allowed to polymerize for a specified, desired cure period. At theend of the cure period, the tray 524 and molds 2 carried therein areretrieved, manually or automatically, from the system 510 for subjectionto further processing steps.

Turning now to FIG. 11, a system 710 for manufacturing contact lenses inaccordance with the invention is shown. This example is provided inorder to provide a general overview of a system in accordance with theinvention that includes many of the different features describedhereinabove.

In this embodiment, the system 710 is somewhat modular in form. Themodular form of this embodiment facilitates maintenance of the system.The system 710 includes two side-by-side “lanes” for simultaneouslyprocessing side-by side trays of molds, such as shown in FIG. 2.

System 710 includes an entrance vestibule 722, a light tunnel assembly724 comprising five light “stations” 726, and an exit vestibule 728. Inanother embodiment, the system comprises six light stations 726.

Each of the two vestibules 722, 728 generally comprises a UV guardedchamber structured to contain a mold filled tray in a substantially UVfree location, both prior to and after the polymerizing process whichtakes place in the light tunnel 724. Between the exit of the entrancevestibule 722 and the first station 726, a UV light shield 730 isprovided for preventing polymerizing amounts of UV light from enteringthe vestibule 722 and polymerizing the lens precursor compositioncontained in the molds. The shield 730 comprises a pneumatic gate 732that moves generally up and down or vertically to allow the tray to passfrom the vestibule 722 to the first light station 726. The exitvestibule 728 is substantially identical to the inlet vestibule 726. Theexit vestibule 728 includes a light shield (not shown) comprising apneumatic gate that is located between the sixth light station and theinlet to the vestibule 728. Additional details regarding structuralfeatures and purposes of the UV blocking vestibules are providedelsewhere herein. The vestibules include a UV blocking or filteringmaterial so that the lens precursor compositions contained in the moldson the tray are not prematurely polymerized by ambient UV light presentin the environment in which the system is placed. The light shield, suchas the gate, helps prevent premature polymerization of the lensprecursor composition by ambient light passing from the curing chamberof the housing.

The light stations 726 may be substantially identical to one another andare structured to be interconnected to define the length of the lighttunnel assembly 724.

Each light station 726 includes a housing 740 containing an upper lightframe assembly 744 holding eight UV lamps, and a substantially opposinglower light frame assembly 746 holding eight UV lamps. Each UV lamp maybe a florescent bulb capable of delivering up to about 2000 μW/cm².

A conveyor system such as described and shown elsewhere herein islocated within the light tunnel assembly 724 and is structured to movethe mold filled trays between the entrance vestibule 722 to the exitvestibule 728. The conveyor assembly is designed to allow molds carriedin the tray to be illuminated from both above and below with asubstantially consistent intensity of UV light.

Each pair of lamps is connected to an electronic ballast (not shown)mounted to a back side of the station housing. The ballasts are eachconnected to a controller 756 and a power source 758. The controller isa computer which receives input from the electronic ballasts. DALI basedprotocol technology is used to detect failure of any of the lamps and isused to set light intensity from the lamps.

The interior surfaces of the housing of the light stations arestructured to provide an “optical surface” effective to reflect anddiffuse light in order to maintain the desired consistent, uniformillumination to the molds in the trays as the trays pass through thelight stations. The optical surfaces comprise an advantageouscombination and arrangement of reflective surfaces and non-reflectivesurfaces. Additional detail regarding the optical surfaces is providedelsewhere herein.

The moving belts of the conveyor system extend a short distance, forexample about 6 inches, into the entrance vestibule and about 6 inchesinto the exit vestibule. The conveyor system is supported by a pluralityof carefully placed supports which are configured and positioned tosupport the conveyor belts without casting significant shadows onto themold filled trays carried by the conveyor. Running along the center ofthe conveyor system is a center support having cantilevered portionsalternating from the left of the support and the right of the support toprovide balance to the center support. The support assembly is describedin greater detail elsewhere herein.

In use, a mold filled tray 24 containing 256 molds (arranged as shown inFIG. 2) is inserted into the entrance vestibule 722. When ready to enterthe first light station, for example, when sufficient space is availableon the conveyor within the first station, the pneumatic gate is opened.Pins, such as retractable pins, of a fast drag arm engage aperturesalong the outermost side of the tray. The arm rapidly pulls the trayinto the first light station where it is placed on the conveyor and thepins retract and disengage from the tray. Movement of the tray from thevestibule to the conveyer takes about fifteen seconds. The fast drag armreturns to the entrance vestibule and the pneumatic gate closes. Thefast drag mechanism is not shown in FIG. 11, but details of a fast dragmechanism are provided elsewhere herein, and shown, for example, in FIG.6.

The tray in the first light station is conveyed to the next station.When moving through the light stations, the tray slowly moves past eachlamp of each station. The tray spends a total time of about one hourmoving from the entrance to the first light station to the exit of thesixth light station. The molds on the tray are illuminated with a UVintensity of about 340 μW/cm². At the end of the sixth light station,the pneumatic gate of the exit vestibule opens, the fast drag armengages the tray and the tray is rapidly pulled into the vestibule. Thefast drag arms disengage the tray and return to the sixth light station.The pneumatic gate closes. The tray can now be removed from the systemfor post processing steps, such as demolding, peeling, extraction andhydration, and lens packaging.

With the arrangement shown in FIG. 11, new mold filled trays can be fedinto the system 710 through the entrance vestibule at a rate of abouttwo side-by-side mold filled trays about every ten minutes, or ifstaggered, one mold filled tray per lane about every 5 minutes.

For example, the trays are placed on each lane in a staggered fashion sothat one tray will be available for pickup from the exit vestibule atany given time.

The light stations can hold 12 trays (i.e. two trays in each of the sixlight stations) and each of the vestibules can hold two trays.

Additional embodiments of the present systems can use other light shielddevices. For example, systems may comprise any element that can block orfilter a major portion of UV light that might cause premature exposureand polymerization of the lens precursor composition in the moldassemblies. The element or elements should be moveable so as to notinterfere with placement of the mold assemblies in the housing or curingchamber. As one additional example, a light shield may be provided thatrotates about an axis to open and close and provide access to the curingchamber. As another example, a flexible curtain or curtains could beused to provide a light barrier to the curing chamber.

Thus, the present systems and methods are effective in polymerizing lensprecursor compositions present in mold assemblies by exposing the lensprecursor compositions to substantially constant and uniform lightintensity during the entire curing process. The light intensity canvary, as discussed herein. For example, the light intensity can vary byabout 5% to about 30% relative to a mean or average light intensityvalue, depending on the particular mean or average light intensity beingutilized.

Certain aspects and advantages of the present invention may be moreclearly understood and/or appreciated with reference to the followingcommonly owned United States patent applications, filed on even dateherewith, the disclosure of each of which is being incorporated hereinin its entirety by this specific reference: U.S. patent application Ser.No. 11/200,848, entitled “Contact Lens Molds and Systems and Methods forProducing Same”, and having attorney docket No. D-4124; U.S. patentapplication Ser. No. 11/200,648, entitled “Contact Lens Mold Assembliesand Systems and Methods of Producing Same”, and having attorney docketNo. D-4125; U.S. patent application Ser. No. 11/201,410, entitled“Systems and Methods for Removing Lenses from Lens Molds”, and havingattorney docket No. D-4127; U.S. patent application Ser. No. 11/200,863,entitled “Contact Lens Extraction/Hydration Systems and Methods ofReprocessing Fluids Used Therein”, and having attorney docket No.D-4128; U.S. patent application Ser. No. 11/200,862, entitled “ContactLens Package”, and having attorney docket No. D-4129; U.S. PatentApplication No. 60/707,029, entitled “Compositions and Methods forProducing Silicone Hydrogel Contact Lenses”, and having attorney docketNo. D-4153P; and U.S. patent application Ser. No. 11/201,409, entitled“Systems and Methods for Producing Silicone Hydrogel Contact Lenses”,and having attorney docket No. D-4154.

A number of publications and patents have been cited hereinabove. Eachof the cited publications and patents are hereby incorporated byreference in their entireties.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

1. A method of producing a silicone hydrogel contact lens, comprising:exposing a contact lens mold assembly, comprising a silicone hydrogellens precursor composition, to ultraviolet light at an ultraviolet lightintensity effective in forming a polymerized silicone hydrogel contactlens, characterized in that the ultraviolet light intensity measured ata surface of the contact lens mold assembly is greater than 20 μW/cm²and less than 4000 μW/cm².
 2. The method of claim 1, wherein theultraviolet light intensity to which the precursor composition isexposed is between 3 μW/cm² and 600 μW/cm².
 3. The method of claim 1,wherein the ultraviolet light intensity measured at the surface of thecontact lens mold assembly is between 100 μW/cm² and 2000 μW/cm².
 4. Themethod of claim 1, wherein the ultraviolet light intensity measured atthe surface of the contact lens mold assembly is between 50 μW/cm² and2000 μW/cm².
 5. The method of claim 4, wherein the ultraviolet lightintensity to which the precursor composition is exposed is between 5μW/cm² and 400 μW/cm².
 6. The method of claim 1, further comprisingplacing the contact lens mold assembly between a first light sourcelocated in a housing of a curing system and a second light sourcelocated in the housing of the curing system so that an upper surface ofthe contact lens mold assembly is exposed to light from the first lightsource and a bottom surface of the contact lens mold assembly is exposedto light from the second light source.
 7. The method of claim 1, whereinthe ultraviolet light intensity varies from 5% to 30% from an averagelight intensity value during the exposure.
 8. The method of claim 1,further comprising monitoring the ultraviolet light intensity using atleast one light sensor device.
 9. The method of claim 1, wherein theexposing occurs for at least 40 minutes.
 10. The method of claim 1,further comprising shielding the contact lens mold assembly frompremature exposure to ultraviolet light prior to the exposing step. 11.The method of claim 1, further comprising controlling distribution ofthe ultraviolet light using a plurality of optical surfaces havingdifferent reflectivities.
 12. The method of claim 1 which comprisesexposing a plurality of contact lens mold assemblies to the ultravioletlight.
 13. A silicone hydrogel contact lens obtained using the method ofclaim
 1. 14. A system for producing a silicone hydrogel contact lens,comprising: an ultraviolet light source that provides ultraviolet lightto a contact lens mold assembly, comprising a silicone hydrogel lensprecursor composition, at an ultraviolet light intensity to form apolymerized silicone hydrogel contact lens, characterized in that theultraviolet light intensity measured at a surface of the contact lensmold assembly is greater than 20 μW/cm² and less than 4000 μW/cm². 15.The system of claim 14, wherein the ultraviolet light intensity to whichthe precursor composition is exposed is between 3 μW/cm² and 600 μW/cm².16. The system of claim 14, wherein the ultraviolet light intensitymeasured at the surface of the contact lens mold assembly is between 100μW/cm² and 2000 μW/cm².
 17. The system of claim 14, wherein theultraviolet light intensity measured at the surface of the contact lensmold assembly is between 50 μW/cm² and 2000 μW/cm².
 18. The method ofclaim 17, wherein the ultraviolet light intensity to which the precursorcomposition is exposed is between 5 μW/cm² and 400 μW/cm².
 19. Thesystem of claim 14, further comprising a housing, and wherein theultraviolet light source comprises a first light source located in thehousing and a second light source located in the housing so that anupper surface of the contact lens mold assembly is exposed to light fromthe first light source and a bottom surface of the contact lens moldassembly is exposed to light from the second light source.
 20. Thesystem of claim 14, further comprising a plurality of optical surfaceshaving different reflectivities effective in controlling the ultravioletlight intensity variability from 5% to 30% from an average lightintensity value.
 21. The system of claim 14, further comprising at leastone light sensor device that monitors the ultraviolet light intensity.22. The system of claim 14, further comprising a conveyor system thatconveys the contact lens mold assembly pass the ultraviolet light sourceto provide light exposure for at least 40 minutes.
 23. The system ofclaim 14, further comprising at least one shield effective in shieldingthe contact lens mold assembly from premature exposure to ultravioletlight.